Ketoreductase polypeptides

ABSTRACT

The present disclosure provides engineered ketoreductase enzymes having improved properties as compared to a naturally occurring wild-type ketoreductase enzyme including the capability of reducing 5-((4S)-2-oxo-4-phenyl (1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to (4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one. Also provided are polynucleotides encoding the engineered ketoreductase enzymes, host cells capable of expressing the engineered ketoreductase enzymes, and methods of using the engineered ketoreductase enzymes to synthesize the intermediate (4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one in a process for making Ezetimibe.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of U.S. patent applicationSer. No. 16/272,507, filed Feb. 11, 2019, now U.S. patent Ser. No.10/544,401, which is a Continuation of U.S. patent application Ser. No.16/031,177, filed Jul. 10, 2018, now U.S. Pat. No. 10,246,687, which isa Continuation of U.S. patent application Ser. No. 15/711,070, filedSep. 21, 2017, now U.S. Pat. No. 10,047,348, which is a Continuation ofU.S. patent application Ser. No. 15/211,505, filed Jul. 15, 2016, nowU.S. Pat. No. 9,796,964, which is a Continuation of U.S. patentapplication Ser. No. 14/824,766, filed Aug. 12, 2015, now U.S. Pat. No.9,422,530, which is a Divisional of U.S. patent application Ser. No.14/606,127, filed Jan. 27, 2015, now U.S. Pat. No. 9,139,820, which is aDivisional of U.S. patent application Ser. No. 13/764,596, filed Feb.11, 2013, now U.S. Pat. No. 8,956,840, which claims priority to U.S.patent application Ser. No. 13/590,882, filed Aug. 21, 2012, whichissued as U.S. Pat. No. 8,415,126 B2 on Apr. 9, 2013, and U.S. patentapplication Ser. No. 12/545,034, filed Aug. 20, 2009, which issued asU.S. Pat. No. 8,273,554 B2 on Sep. 25, 2012, and U.S. Provisional Appln.Ser. No. 61/092,807, filed Aug. 29, 2008, each of which is herebyincorporated by reference herein.

1. TECHNICAL FIELD

The present disclosure relates to engineered polypeptides and uses ofthe polypeptides for preparing the intermediate(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-onein a process for making Ezetimibe.

2. REFERENCE TO SEQUENCE LISTING, TABLE OR COMPUTER PROGRAM

The Sequence Listing concurrently submitted electronically under 37C.F.R. § 1.821 via EFS-Web in a computer readable form (CRF) as filename CX2-025USD1D3C1_Substitute_ST25.txt is herein incorporated byreference. The electronic copy of the Sequence Listing was created onSep. 15, 2016, with a file size of 301 Kbytes.

3. BACKGROUND

Enzymes belonging to the ketoreductase (KRED) or carbonyl reductaseclass (EC1.1.1.184) are useful for the synthesis of optically activealcohols from the corresponding prostereoisomeric ketone substrates andby stereospecific reduction of corresponding racemic aldehyde and ketonesubstrates. KREDs typically convert a ketone or aldehyde substrate tothe corresponding alcohol product, but may also catalyze the reversereaction, oxidation of an alcohol substrate to the correspondingketone/aldehyde product. The reduction of ketones and aldehydes and theoxidation of alcohols by enzymes such as KRED requires a co-factor, mostcommonly reduced nicotinamide adenine dinucleotide (NADH) or reducednicotinamide adenine dinucleotide phosphate (NADPH), and nicotinamideadenine dinucleotide (NAD) or nicotinamide adenine dinucleotidephosphate (NADP) for the oxidation reaction. NADH and NADPH serve aselectron donors, while NAD and NADP serve as electron acceptors. It isfrequently observed that ketoreductases and alcohol dehydrogenasesaccept either the phosphorylated or the non-phosphorylated co-factor (inits oxidized and reduced state).

KRED enzymes can be found in a wide range of bacteria and yeasts (forreviews: Kraus and Waldman, Enzyme catalysis in organic synthesis Vols.1&2. VCH Weinheim 1995; Faber, K., Biotransformations in organicchemistry, 4th Ed. Springer, Berlin Heidelberg New York. 2000; Hummeland Kula Eur. J. Biochem. 1989 184:1-13). Several KRED gene and enzymesequences have been reported, e.g., Candida magnoliae (Genbank Acc. No.JC7338; GI:11360538) Candida parapsilosis (Genbank Acc. No. BAA24528.1;GI:2815409), Sporobolomyces salmonicolor (Genbank Acc. No. AF160799;GI:6539734).

In order to circumvent many chemical synthetic procedures for theproduction of key compounds, ketoreductases are being increasinglyemployed for the enzymatic conversion of different keto and aldehydesubstrates to chiral alcohol products. These applications can employwhole cells expressing the ketoreductase for biocatalytic ketonereductions, or purified enzymes in those instances where presence ofmultiple ketoreductases in whole cells would adversely affect thestereopurity and yield of the desired product. For in vitroapplications, a co-factor (NADH or NADPH) regenerating enzyme such asglucose dehydrogenase (GDH), formate dehydrogenase etc. is used inconjunction with the ketoreductase. Examples using ketoreductases togenerate useful chemical compounds include asymmetric reduction of4-chloroacetoacetate esters (Zhou, J. Am. Chem. Soc. 1983 105:5925-5926;Santaniello, J. Chem. Res. (S) 1984:132-133; U.S. Pat. Nos. 5,559,030;5,700,670 and 5,891,685), reduction of dioxocarboxylic acids (e.g., U.S.Pat. No. 6,399,339), reduction of tert-butyl (S)chloro-5-hydroxy-3-oxohexanoate (e.g., U.S. Pat. No. 6,645,746 and WO01/40450), reduction pyrrolotriazine-based compounds (e.g., U.S.application No. 2006/0286646); reduction of substituted acetophenones(e.g., U.S. Pat. No. 6,800,477); and reduction of ketothiolanes (WO2005/054491).

It is desirable to identify other ketoreductase enzymes that can be usedto carry out conversion of various keto substrates to its correspondingchiral alcohol products.

4. SUMMARY

The present disclosure provides ketoreductase polypeptides capable ofreducing 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione (“thesubstrate”) to(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one(“the product”), polynucleotides encoding such polypeptides, and methodsfor using the polypeptides. The ketoreductase polypeptides are alsocapable of reducing1-(4-fluorophenyl)-3(R)-[3-oxo-3-(4-fluorophenyl)propyl)]-4(S)-(4-hydroxyphenyl)-2-azetidinone,to the corresponding stereoisomeric alcohol1-(4-fluorophenyl)-3(R)-[3(S)-hydroxy-3(4-fluorophenyl)-propyl)]-4(S)-(4-hydroxyphenyl)-2-azetidinone.

In one aspect, the ketoreductase polypeptides described herein have anamino acid sequence that has one or more amino acid differences ascompared to a reference amino acid sequence of a wild-type ketoreductaseor an engineered ketoreductase that result in an improved property ofthe enzyme for the defined keto substrate. Generally, the engineeredketoreductase polypeptides have an improved property as compared to thenaturally-occurring wild-type ketoreductase enzymes obtained fromLactobacillus kefir (“L. kefir”; SEQ ID NO:4), Lactobacillus brevis (“L.brevis”; SEQ ID NO:2), and Lactobacillus minor (“L. minor”; SEQ IDNO:158). In some embodiments, the polypeptides of the disclosure have animproved property as compared to another engineered polypeptide, such asSEQ ID NO: 8. Improvements in enzyme property include increases inenzyme activity, stereoselectivity, sterospecificity, thermostability,solvent stability, or reduced product inhibition. In the presentdisclosure, the ketoreductase polypeptides have at least the followingamino acid sequence as compared to the amino acid sequence of SEQ IDNO:2, 4, or 158: the amino acid residue corresponding to X145 is aserine, and the amino acid residue corresponding to X190 is a cysteine.In some embodiments, as compared to the sequences of SEQ ID NO: 2, 4, or158, the ketoreductase polypeptides have at least the following aminoacid sequence differences: (1) the amino acid residue corresponding toX145 is a serine; the amino acid residue corresponding to residue X190is a cysteine; and the amino acid residue corresponding to X96 is aglutamine. In some embodiments, as compared to the sequence of SEQ IDNO:2, 4, or 158, the ketoreductase polypeptides have at least the aminoacid sequence as compared to the amino acid sequence of SEQ ID NO:2, 4,or 158: residue X145 is a serine; residue X190 is a cysteine, andresidue X211 is an arginine.

In some embodiments, the ketoreductase polypeptides of the invention areimproved as compared to SEQ ID NO:2, 4 or 158 with respect to their rateof enzymatic activity, i.e., their rate of converting the substrate tothe product. In some embodiments, the ketoreductase polypeptides arecapable of converting the substrate to the product at a rate that is atleast 1.5-times, 2-times, 3-times, 4-times, 5-times, 10-times, 25-times,50-times, 100-times, 150-times, 200-times, 400-times, 1000-times,3000-times, 5000-times, 7000-times or more than 7000-times the rateexhibited by the enzyme of SEQ ID NO:2, 4 or 158.

In some embodiments, the ketoreductase polypeptide is capable ofconverting the substrate 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to theproduct(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one,at a rate that is improved over a reference polypeptide having the aminoacid sequence of SEQ ID NO:8. In some embodiments, such ketoreductasepolypeptides are also capable of converting the substrate to the productwith a percent stereomeric excess of at least about 95%. In someembodiments, such ketoreductase polypeptides are also capable ofconverting the substrate to the product with a percent stereomericexcess of at least about 99%. Exemplary polypeptides with suchproperties include, but are not limited to, polypeptides whichcomprising amino acid sequences corresponding to SEQ ID NO: 42, 44, 46,50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84,86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116,118, 120, 122, 124, and 126.

In some embodiments, the ketoreductase polypeptide is capable ofconverting the substrate 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to theproduct(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one,with a percent stereomeric excess of at least about 99% and at a ratethat is at least about 5 times or more improved over a referencepolypeptide having the amino acid sequence of SEQ ID NO:8. Exemplarypolypeptides with such properties include, but are not limited to,polypeptides which comprise an amino acid sequence corresponding to SEQID NO: 42, 44, 46, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74,76, 78, 80, 82, 84, 86, 88, 90, 92, 96, 98, 100, 102, 104, 106, 108,110, 112, 114, 116, 118, 120, 122, 124, and 126.

In some embodiments, the ketoreductase polypeptide is capable ofconverting the substrate 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to theproduct(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one,with a percent stereomeric excess of at least about 99% and at a ratethat is at least about 3000 to about 7000 times improved over areference polypeptide having the amino acid sequence of SEQ ID NO:8.Exemplary polypeptides with such properties include, but are not limitedto, polypeptides which comprise an amino acid sequence corresponding toSEQ ID NO: 44, 46, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 72, 74, 78,80, 82, 84, and 86.

In some embodiments, the ketoreductase polypeptide is capable ofconverting the substrate 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to theproduct(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one,with a percent stereomeric excess of at least about 99% and at a ratethat is at least 7000 times improved over a reference polypeptide havingthe amino acid sequence of SEQ ID NO:8. Exemplary polypeptides with suchproperties include, but are not limited to, polypeptides which compriseamino acid sequences corresponding to SEQ ID NO: 102, 108, 120, 122,124, and 126.

In some embodiments, the ketoreductase polypeptide is capable ofconverting at least about 95% of the substrate to the product in lessthan about 24 hours when carried out with greater than about 100 g/L ofsubstrate and less than about 5 g/L of the polypeptide. Exemplarypolypeptides that have this capability include, but are not limited to,polypeptides which comprise amino acid sequences corresponding to SEQ IDNO: 102, 108, 120, 122, 124, and 126.

In some embodiments, the ketoreductase polypeptide is highlystereoselective, wherein the polypeptide can reduce the substrate to theproduct in greater than about 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%,99.6%, 99.7%, 99.8% or 99.9% stereomeric excess. Exemplary ketoreductasepolypeptides with high stereoselectivity include, but are not limitedto, the polypeptides comprising the amino acid sequences correspondingto SEQ ID NO: 42, 44, 46, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70,72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 96, 98, 100, 102, 104, 106,108, 110, 112, 114, 116, 118, 120, 122, 124, and 126.

In some embodiments, an improved ketoreductase polypeptide comprises anamino acid sequence that corresponds to the sequence formulas of SEQ IDNO:161, 162 or 163 (or a region thereof, such as residues 90-211). SEQID NO:162 is based on the amino acid sequence of the Lactobacillus kefirketoreductase of SEQ ID NO:4. The sequence formula of SEQ ID NO:161 isbased on the amino acid sequence of the Lactobacillus brevisketoreductase (SEQ ID NO:2). The sequence formula of SEQ ID NO:163 isbased on the amino acid sequence of the Lactobacillus minorketoreductase (SEQ ID NO:158). SEQ ID NO:161, 162 or 163 specify thatresidue X145 is a polar residue and residue X190 is cysteine.

In some embodiments, an improved ketoreductase polypeptide of thedisclosure is based on the sequence formulas of SEQ ID NO:161, 162 or163 and can comprise an amino acid sequence that is at least about 85%,86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identical to the reference sequence of SEQ ID NO:128, 130, or 160, withthe proviso that the ketoreductase amino acid sequence has at theresidue corresponding to residue X145 a serine and at the amino acidresidue corresponding to X190 a cysteine. In some embodiments, theketoreductase polypeptides can have one or more amino acid residuedifferences as compared to SEQ ID NO:128, 130, or 160. These differencescan be amino acid insertions, deletions, substitutions, or anycombination of such changes. In some embodiments, the amino acidsequence differences can comprise non-conservative, conservative, aswell as a combination of non-conservative and conservative amino acidsubstitutions. Various amino acid residue positions where such changescan be made are described herein.

In some embodiments, an improved ketoreductase polypeptide is based onthe sequence formulas of SEQ ID NO:161, 162 or 163 and can comprise aregion having an amino acid sequence that is at least about 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identical to a region or domain thereof, such as residues 90-211 of thereference sequence of SEQ ID NO:128, 130, or 160, with the proviso thatthe ketoreductase polypeptide amino acid sequence has at the residuecorresponding to residue X145 a serine and at the amino acid residuecorresponding to X190 a cysteine. In some embodiments, the amino acidsequence differences can comprise non-conservative, conservative, aswell as a combination of non-conservative and conservative amino acidsubstitutions. Various amino acid residue positions where such changescan be made in the defined region are described herein.

In some embodiments, an improved ketoreductase comprises an amino acidsequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%,93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acidsequence corresponding to SEQ ID NO: 8, 42, 44, 46, 50, 52, 54, 56, 58,60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94,96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124,and 126, wherein the improved ketoreductase polypeptide amino acidsequence includes any one set of the specified amino acid substitutioncombinations presented in Tables 3 and 4. In some embodiments, theseketoreductase polypeptides can have mutations at other amino acidresidues.

In another aspect, the present disclosure provides polynucleotidesencoding the engineered ketoreductases described herein orpolynucleotides that hybridize to such polynucleotides under highlystringent conditions. The polynucleotide can include promoters and otherregulatory elements useful for expression of the encoded engineeredketoreductase, and can utilize codons optimized for specific desiredexpression systems. In some embodiments, the polynucleotides encode aketoreductase polypeptides having at least the following amino acidsequence as compared to the amino acid sequence of SEQ ID NO:2, 4, or158: the amino acid residue corresponding to X145 is a serine, and theamino acid residue corresponding to X190 is a cysteine. Exemplarypolynucleotides include, but are not limited to, a polynucleotidesequence of SEQ ID NO: 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63,65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99,101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 121, 123, and 125.

In another aspect, the present disclosure provides host cells comprisingthe polynucleotides and/or expression vectors described herein. The hostcells may be L. kefir or L. brevis, or they may be a different organism,and as E. coli. The host cells can be used for the expression andisolation of the engineered ketoreductase enzymes described herein, or,alternatively, they can be used directly for the conversion of thesubstrate to the stereoisomeric product.

Whether carrying out the method with whole cells, cell extracts orpurified ketoreductase enzymes, a single ketoreductase enzyme may beused or, alternatively, mixtures of two or more ketoreductase enzymesmay be used.

The ketoreductase enzymes described herein are capable of catalyzing thereduction reaction of the keto group in the compound of structuralformula (I), 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione (“thesubstrate”),

to the corresponding stereoisomeric alcohol product of structuralformula (II),(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one(“the product”):

In some embodiments, the method for reducing or converting the substratehaving the structural formula (I) to the corresponding product ofstructural formula (II) comprises contacting or incubating the substratewith a ketoreductase polypeptide disclosed herein under reactionconditions suitable for reducing or converting the substrate to theproduct.

In some embodiment, the ketoreductase enzymes described herein are alsocapable of catalyzing the reduction reaction of the keto group in thecompound of structural formula (III), 1-(4-fluorophenyl)-3(R)-[3-oxo-3-(4-fluorophenyl)propyl)]-4(S)-(4-hydroxyphenyl)-2-azetidinone,

to the corresponding stereoisomeric alcohol product of structuralformula (IV),1-(4-fluorophenyl)-3(R)-[3(S)-hydroxy-3(4-fluorophenyl)-propyl)]-4(S)-(4-hydroxyphenyl)-2-azetidinone,

In some embodiments, the method for reducing the substrate having thestructural formula (III) to the corresponding product of structuralformula (IV) comprises contacting or incubating the compound of formula(III) with a ketoreductase polypeptide disclosed herein under reactionconditions suitable for reducing or converting the substrate of formula(III) to the product of formula (IV).

In some embodiments of this method for reducing the substrate to theproduct, the substrate is reduced to the product in greater than about99% stereomeric excess, wherein the ketoreductase polypeptide comprisesa sequence that corresponds to SEQ ID NO: SEQ ID NO: 42, 44, 46, 50, 52,54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88,90, 92, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120,122, 124, and 126.

In some embodiments of this method for reducing the substrate to theproduct, at least about 95% of the substrate is converted to the productin less than about 24 hours when carried out with greater than about 100g/L of substrate and less than about 5 g/L of the polypeptide, whereinthe polypeptide comprises an amino acid sequence corresponding to SEQ IDNO: 102, 108, 120, 122, 124, or 126.

5. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates the role of ketoreductases (KRED) in the conversionof the substrate compound of formula (I) to the corresponding product offormula (II). This reduction uses a KRED of the invention and aco-factor such as NADPH. A glucose dehydrogenase (GDH) is used tocovert/recycle NADP⁺ to NADPH. Glucose is converted to gluconic acid,which in turn is converted to its sodium salt (sodium gluconate) withthe addition of sodium hydroxide.

6. DETAILED DESCRIPTION 6.1 Definitions

As used herein, the following terms are intended to have the followingmeanings.

“Ketoreductase” and “KRED” are used interchangeably herein to refer to apolypeptide having an enzymatic capability of reducing a carbonyl groupto its corresponding alcohol. More specifically, the ketoreductasepolypeptides of the invention are capable of stereoselectively reducingthe compound of formula (I), supra to the corresponding product offormula (II), supra. The polypeptide typically utilizes a cofactorreduced nicotinamide adenine dinucleotide (NADH) or reduced nicotinamideadenine dinucleotide phosphate (NADPH) as the reducing agent.Ketoreductases as used herein include naturally occurring (wild type)ketoreductases as well as non-naturally occurring engineeredpolypeptides generated by human manipulation.

“Coding sequence” refers to that portion of a nucleic acid (e.g., agene) that encodes an amino acid sequence of a protein.

“Naturally-occurring” or “wild-type” refers to the form found in nature.For example, a naturally occurring or wild-type polypeptide orpolynucleotide sequence is a sequence present in an organism that can beisolated from a source in nature and which has not been intentionallymodified by human manipulation.

“Recombinant” when used with reference to, e.g., a cell, nucleic acid,or polypeptide, refers to a material, or a material corresponding to thenatural or native form of the material, that has been modified in amanner that would not otherwise exist in nature, or is identical theretobut produced or derived from synthetic materials and/or by manipulationusing recombinant techniques. Non-limiting examples include, amongothers, recombinant cells expressing genes that are not found within thenative (non-recombinant) form of the cell or express native genes thatare otherwise expressed at a different level.

“Percentage of sequence identity” and “percentage homology” are usedinterchangeably herein to refer to comparisons among polynucleotides andpolypeptides, and are determined by comparing two optimally alignedsequences over a comparison window, wherein the portion of thepolynucleotide or polypeptide sequence in the comparison window maycomprise additions or deletions (i.e., gaps) as compared to thereference sequence (which does not comprise additions or deletions) foroptimal alignment of the two sequences. The percentage may be calculatedby determining the number of positions at which the identical nucleicacid base or amino acid residue occurs in both sequences to yield thenumber of matched positions, dividing the number of matched positions bythe total number of positions in the window of comparison andmultiplying the result by 100 to yield the percentage of sequenceidentity. Alternatively, the percentage may be calculated by determiningthe number of positions at which either the identical nucleic acid baseor amino acid residue occurs in both sequences or a nucleic acid base oramino acid residue is aligned with a gap to yield the number of matchedpositions, dividing the number of matched positions by the total numberof positions in the window of comparison and multiplying the result by100 to yield the percentage of sequence identity. Those of skill in theart appreciate that there are many established algorithms available toalign two sequences. Optimal alignment of sequences for comparison canbe conducted, e.g., by the local homology algorithm of Smith andWaterman, 1981, Adv. Appl. Math. 2:482, by the homology alignmentalgorithm of Needleman and Wunsch, 1970, J. Mol. Biol. 48:443, by thesearch for similarity method of Pearson and Lipman, 1988, Proc. Natl.Acad. Sci. USA 85:2444, by computerized implementations of thesealgorithms (GAP, BESTFIT, FASTA, and TFASTA in the GCG WisconsinSoftware Package), or by visual inspection (see generally, CurrentProtocols in Molecular Biology, F. M. Ausubel et al., eds., CurrentProtocols, a joint venture between Greene Publishing Associates, Inc.and John Wiley & Sons, Inc., (1995 Supplement) (Ausubel)). Examples ofalgorithms that are suitable for determining percent sequence identityand sequence similarity are the BLAST and BLAST 2.0 algorithms, whichare described in Altschul et al., 1990, J. Mol. Biol. 215: 403-410 andAltschul et al., 1977, Nucleic Acids Res. 3389-3402, respectively.Software for performing BLAST analyses is publicly available through theNational Center for Biotechnology Information website. This algorithminvolves first identifying high scoring sequence pairs (HSPs) byidentifying short words of length W in the query sequence, which eithermatch or satisfy some positive-valued threshold score T when alignedwith a word of the same length in a database sequence. T is referred toas, the neighborhood word score threshold (Altschul et al, supra). Theseinitial neighborhood word hits act as seeds for initiating searches tofind longer HSPs containing them. The word hits are then extended inboth directions along each sequence for as far as the cumulativealignment score can be increased. Cumulative scores are calculatedusing, for nucleotide sequences, the parameters M (reward score for apair of matching residues; always >0) and N (penalty score formismatching residues; always <0). For amino acid sequences, a scoringmatrix is used to calculate the cumulative score. Extension of the wordhits in each direction are halted when: the cumulative alignment scorefalls off by the quantity X from its maximum achieved value; thecumulative score goes to zero or below, due to the accumulation of oneor more negative-scoring residue alignments; or the end of eithersequence is reached. The BLAST algorithm parameters W, T, and Xdetermine the sensitivity and speed of the alignment. The BLASTN program(for nucleotide sequences) uses as defaults a wordlength (W) of 11, anexpectation (E) of 10, M=5, N=−4, and a comparison of both strands. Foramino acid sequences, the BLASTP program uses as defaults a wordlength(W) of 3, an expectation (E) of 10, and the BLOSUM62 scoring matrix (seeHenikoff and Henikoff, 1989, Proc Natl Acad Sci USA 89:10915). Exemplarydetermination of sequence alignment and % sequence identity can employthe BESTFIT or GAP programs in the GCG Wisconsin Software package(Accelrys, Madison Wis.), using default parameters provided.

“Reference sequence” refers to a defined sequence used as a basis for asequence comparison. A reference sequence may be a subset of a largersequence, for example, a segment of a full-length gene or polypeptidesequence. Generally, a reference sequence is at least 20 nucleotide oramino acid residues in length, at least 25 residues in length, at least50 residues in length, or the full length of the nucleic acid orpolypeptide. Since two polynucleotides or polypeptides may each (1)comprise a sequence (i.e., a portion of the complete sequence) that issimilar between the two sequences, and (2) may further comprise asequence that is divergent between the two sequences, sequencecomparisons between two (or more) polynucleotides or polypeptide aretypically performed by comparing sequences of the two polynucleotidesover a “comparison window” to identify and compare local regions ofsequence similarity.

“Comparison window” refers to a conceptual segment of at least about 20contiguous nucleotide positions or amino acids residues wherein asequence may be compared to a reference sequence of at least 20contiguous nucleotides or amino acids and wherein the portion of thesequence in the comparison window may comprise additions or deletions(i.e., gaps) of 20 percent or less as compared to the reference sequence(which does not comprise additions or deletions) for optimal alignmentof the two sequences. The comparison window can be longer than 20contiguous residues, and includes, optionally 30, 40, 50, 100, or longerwindows.

“Substantial identity” refers to a polynucleotide or polypeptidesequence that has at least 80 percent sequence identity, at least 85percent identity and 89 to 95 percent sequence identity, more usually atleast 99 percent sequence identity as compared to a reference sequenceover a comparison window of at least 20 residue positions, frequentlyover a window of at least 30-50 residues, wherein the percentage ofsequence identity is calculated by comparing the reference sequence to asequence that includes deletions or additions which total 20 percent orless of the reference sequence over the window of comparison. Inspecific embodiments applied to polypeptides, the term “substantialidentity” means that two polypeptide sequences, when optimally aligned,such as by the programs GAP or BESTFIT using default gap weights, shareat least 80 percent sequence identity, preferably at least 89 percentsequence identity, at least 95 percent sequence identity or more (e.g.,99 percent sequence identity). Preferably, residue positions which arenot identical differ by conservative amino acid substitutions.

“Corresponding to”, “reference to” or “relative to” when used in thecontext of the numbering of a given amino acid or polynucleotidesequence refers to the numbering of the residues of a specifiedreference sequence when the given amino acid or polynucleotide sequenceis compared to the reference sequence. In other words, the residuenumber or residue position of a given polymer is designated with respectto the reference sequence rather than by the actual numerical positionof the residue within the given amino acid or polynucleotide sequence.For example, a given amino acid sequence, such as that of an engineeredketoreductase, can be aligned to a reference sequence by introducinggaps to optimize residue matches between the two sequences. In thesecases, although the gaps are present, the numbering of the residue inthe given amino acid or polynucleotide sequence is made with respect tothe reference sequence to which it has been aligned.

“Stereoselectivity” refers to the preferential formation in a chemicalor enzymatic reaction of one stereoisomer over another.Stereoselectivity can be partial, where the formation of onestereoisomer is favored over the other, or it may be complete where onlyone stereoisomer is formed. When the stereoisomers are enantiomers, thestereoselectivity is referred to as enantioselectivity, the fraction(typically reported as a percentage) of one enantiomer in the sum ofboth. It is commonly alternatively reported in the art (typically as apercentage) as the enantiomeric excess (e.e.) calculated therefromaccording to the formula [major enantiomer−minor enantiomer]/[majorenantiomer+minor enantiomer]. Where the stereoisomers arediastereoisomers, the stereo selectivity is referred to asdiastereoselectivity, the fraction (typically reported as a percentage)of one diastereomer in a mixture of two diasteromers, commonlyalternatively reported as the diastereomeric excess (d.e.). Enantiomericexcess and diastereomeric excess are types of stereomeric excess.

“Highly stereoselective”: refers to a ketoreductase polypeptide that iscapable of converting or reducing the substrate to the corresponding(S)-product with at least about 99% stereomeric excess.

“Stereospecificity” refers to the preferential conversion in a chemicalor enzymatic reaction of one stereoisomer over another.Stereospecificity can be partial, where the conversion of onestereoisomer is favored over the other, or it may be complete where onlyone stereoisomer is converted.

“Chemoselectivity” refers to the preferential formation in a chemical orenzymatic reaction of one product over another.

“Improved enzyme property” refers to a ketoreductase polypeptide thatexhibits an improvement in any enzyme property as compared to areference ketoreductase. For the engineered ketoreductase polypeptidesdescribed herein, the comparison is generally made to the wild-typeketoreductase enzyme, although in some embodiments, the referenceketoreductase can be another improved engineered ketoreductase. Enzymeproperties for which improvement is desirable include, but are notlimited to, enzymatic activity (which can be expressed in terms ofpercent conversion of the substrate), thermal stability, pH activityprofile, cofactor requirements, refractoriness to inhibitors (e.g.,product inhibition), stereospecificity, and stereoselectivity (includingenantioselectivity).

“Increased enzymatic activity” refers to an improved property of theengineered ketoreductase polypeptides, which can be represented by anincrease in specific activity (e.g., product produced/time/weightprotein) or an increase in percent conversion of the substrate to theproduct (e.g., percent conversion of starting amount of substrate toproduct in a specified time period using a specified amount of KRED) ascompared to the reference ketoreductase enzyme. Exemplary methods todetermine enzyme activity are provided in the Examples. Any propertyrelating to enzyme activity may be affected, including the classicalenzyme properties of K_(m), V_(max) or k_(cat), changes of which canlead to increased enzymatic activity. Improvements in enzyme activitycan be from about 1.5 times the enzymatic activity of the correspondingwild-type ketoreductase enzyme, to as much as 2 times. 5 times, 10times, 20 times, 25 times, 50 times, 75 times, 100 times, 150 times, 200times, 500 times, 1000, times, 3000 times, 5000 times, 7000 times ormore enzymatic activity than the naturally occurring ketoreductase oranother engineered ketoreductase from which the ketoreductasepolypeptides were derived. In specific embodiments, the engineeredketoreductase enzyme exhibits improved enzymatic activity in the rangeof 150 to 3000 times, 3000 to 7000 times, or more than 7000 timesgreater than that of the parent ketoreductase enzyme. It is understoodby the skilled artisan that the activity of any enzyme is diffusionlimited such that the catalytic turnover rate cannot exceed thediffusion rate of the substrate, including any required cofactors. Thetheoretical maximum of the diffusion limit, or k_(cat)/K_(m), isgenerally about 10⁸ to 10⁹ (M⁻¹ s⁻¹). Hence, any improvements in theenzyme activity of the ketoreductase will have an upper limit related tothe diffusion rate of the substrates acted on by the ketoreductaseenzyme. Ketoreductase activity can be measured by any one of standardassays used for measuring ketoreductase, such as a decrease inabsorbance or fluorescence of NADPH due to its oxidation with theconcomitant reduction of a ketone to an alcohol, or by product producedin a coupled assay. Comparisons of enzyme activities are made using adefined preparation of enzyme, a defined assay under a set condition,and one or more defined substrates, as further described in detailherein. Generally, when lysates are compared, the numbers of cells andthe amount of protein assayed are determined as well as use of identicalexpression systems and identical host cells to minimize variations inamount of enzyme produced by the host cells and present in the lysates.

“Conversion”: refers to the enzymatic reduction of the substrate to thecorresponding product. “Percent conversion” refers to the percent of thesubstrate that is reduced to the product within a period of time underspecified conditions. Thus, the “enzymatic activity” or “activity” of aketoreductase polypeptide can be expressed as “percent conversion” ofthe substrate to the product.

“Thermostable” refers to a ketoreductase polypeptide that maintainssimilar activity (more than 60% to 80% for example) after exposure toelevated temperatures (e.g. 40-80° C.) for a period of time (e.g. 0.5-24hrs) compared to the untreated enzyme.

“Solvent stable” refers to a ketoreductase polypeptide that maintainssimilar activity (more than e.g., 60% to 80%) after exposure to varyingconcentrations (e.g., 5-99%) of solvent (isopropyl alcohol,tetrahydrofuran, 2-methyltetrahydrofuran, acetone, toluene,butylacetate, methyl tert-butylether, etc.) for a period of time (e.g.,0.5-24 hrs) compared to the untreated enzyme.

“pH stable” refers to a ketoreductase polypeptide that maintains similaractivity (more than e.g., 60% to 80%) after exposure to high or low pH(e.g., 4.5-6 or 8 to 12) for a period of time (e.g., 0.5-24 hrs)compared to the untreated enzyme.

“Thermo- and solvent stable” refers to a ketoreductase polypeptide thatis both thermostable and solvent stable.

“Derived from” as used herein in the context of engineered ketoreductaseenzymes, identifies the originating ketoreductase enzyme, and/or thegene encoding such ketoreductase enzyme, upon which the engineering wasbased. For example, the engineered ketoreductase enzyme of SEQ ID NO:158was obtained by artificially evolving, over multiple generations thegene encoding the Lactobacillus kefir ketoreductase enzyme of SEQ IDNO:4. Thus, this engineered ketoreductase enzyme is “derived from” thewild-type ketoreductase of SEQ ID NO:4.

“Hydrophilic Amino Acid or Residue” refers to an amino acid or residuehaving a side chain exhibiting a hydrophobicity of less than zeroaccording to the normalized consensus hydrophobicity scale of Eisenberget al., 1984, J. Mol. Biol. 179:125-142. Genetically encoded hydrophilicamino acids include L-Thr (T), L-Ser (S), L-His (H), L-Glu (E), L-Asn(N), L-Gln (Q), L-Asp (D), L-Lys (K) and L-Arg (R).

“Acidic Amino Acid or Residue” refers to a hydrophilic amino acid orresidue having a side chain exhibiting a pK value of less than about 6when the amino acid is included in a peptide or polypeptide. Acidicamino acids typically have negatively charged side chains atphysiological pH due to loss of a hydrogen ion. Genetically encodedacidic amino acids include L-Glu (E) and L-Asp (D).

“Basic Amino Acid or Residue” refers to a hydrophilic amino acid orresidue having a side chain exhibiting a pK value of greater than about6 when the amino acid is included in a peptide or polypeptide. Basicamino acids typically have positively charged side chains atphysiological pH due to association with hydronium ion. Geneticallyencoded basic amino acids include L-Arg (R) and L-Lys (K).

“Polar Amino Acid or Residue” refers to a hydrophilic amino acid orresidue having a side chain that is uncharged at physiological pH, butwhich has at least one bond in which the pair of electrons shared incommon by two atoms is held more closely by one of the atoms.Genetically encoded polar amino acids include L-Asn (N), L-Gln (Q),L-Ser (S) and L-Thr (T).

“Hydrophobic Amino Acid or Residue” refers to an amino acid or residuehaving a side chain exhibiting a hydrophobicity of greater than zeroaccording to the normalized consensus hydrophobicity scale of Eisenberget al., 1984, J. Mol. Biol. 179:125-142. Genetically encoded hydrophobicamino acids include L-Pro (P), L-Ile (I), L-Phe (F), L-Val (V), L-Leu(L), L-Trp (W), L-Met (M), L-Ala (A) and L-Tyr (Y).

“Aromatic Amino Acid or Residue” refers to a hydrophilic or hydrophobicamino acid or residue having a side chain that includes at least onearomatic or heteroaromatic ring. Genetically encoded aromatic aminoacids include L-Phe (F), L-Tyr (Y) and L-Trp (W). Although owing to thepKa of its heteroaromatic nitrogen atom L-His (H) it is sometimesclassified as a basic residue, or as an aromatic residue as its sidechain includes a heteroaromatic ring, herein histidine is classified asa hydrophilic residue or as a “constrained residue” (see below).

“Constrained amino acid or residue” refers to an amino acid or residuethat has a constrained geometry. Herein, constrained residues includeL-pro (P) and L-his (H). Histidine has a constrained geometry because ithas a relatively small imidazole ring. Proline has a constrainedgeometry because it also has a five membered ring.

“Non-polar Amino Acid or Residue” refers to a hydrophobic amino acid orresidue having a side chain that is uncharged at physiological pH andwhich has bonds in which the pair of electrons shared in common by twoatoms is generally held equally by each of the two atoms (i.e., the sidechain is not polar). Genetically encoded non-polar amino acids includeL-Gly (G), L-Leu (L), L-Val (V), L-Ile (I), L-Met (M) and L-Ala (A).

“Aliphatic Amino Acid or Residue” refers to a hydrophobic amino acid orresidue having an aliphatic hydrocarbon side chain. Genetically encodedaliphatic amino acids include L-Ala (A), L-Val (V), L-Leu (L) and L-Ile(I).

“Cysteine”. The amino acid L-Cys (C) is unusual in that it can formdisulfide bridges with other L-Cys (C) amino acids or other sulfanyl- orsulfhydryl-containing amino acids. The “cysteine-like residues” includecysteine and other amino acids that contain sulfhydryl moieties that areavailable for formation of disulfide bridges. The ability of L-Cys (C)(and other amino acids with —SH containing side chains) to exist in apeptide in either the reduced free —SH or oxidized disulfide-bridgedform affects whether L-Cys (C) contributes net hydrophobic orhydrophilic character to a peptide. While L-Cys (C) exhibits ahydrophobicity of 0.29 according to the normalized consensus scale ofEisenberg (Eisenberg et al., 1984, supra), it is to be understood thatfor purposes of the present disclosure L-Cys (C) is categorized into itsown unique group.

“Small Amino Acid or Residue” refers to an amino acid or residue havinga side chain that is composed of a total three or fewer carbon and/orheteroatoms (excluding the α-carbon and hydrogens). The small aminoacids or residues may be further categorized as aliphatic, non-polar,polar or acidic small amino acids or residues, in accordance with theabove definitions. Genetically-encoded small amino acids include L-Ala(A), L-Val (V), L-Cys (C), L-Asn (N), L-Ser (S), L-Thr (T) and L-Asp(D).

“Hydroxyl-containing Amino Acid or Residue” refers to an amino acidcontaining a hydroxyl (—OH) moiety. Genetically-encodedhydroxyl-containing amino acids include L-Ser (S) L-Thr (T) and L-Tyr(Y).

“Conservative” amino acid substitutions or mutations refer to theinterchangeability of residues having similar side chains, and thustypically involves substitution of the amino acid in the polypeptidewith amino acids within the same or similar defined class of aminoacids. However, as used herein, conservative mutations do not includesubstitutions from a hydrophilic to hydrophilic, hydrophobic tohydrophobic, hydroxyl-containing to hydroxyl-containing, or small tosmall residue, if the conservative mutation can instead be asubstitution from an aliphatic to an aliphatic, non-polar to non-polar,polar to polar, acidic to acidic, basic to basic, aromatic to aromatic,or constrained to constrained residue. Further, as used herein, A, V, L,or I can be conservatively mutated to either another aliphatic residueor to another non-polar residue. Table 1 below shows exemplaryconservative substitutions.

TABLE 1 Conservative Substitutions Residue Possible ConservativeMutations A, L, V, I Other aliphatic (A, L, V, I) Other non-polar (A, L,V, I, G, M) G, M Other non-polar (A, L, V, I, G, M) D, E Other acidic(D, E) K, R Other basic (K, R) P, H Other constrained (P, H) N, Q, S, TOther polar (N, Q, S, T) Y, W, F Other aromatic (Y, W, F) C None

“Non-conservative substitution” refers to substitution or mutation of anamino acid in the polypeptide with an amino acid with significantlydiffering side chain properties. Non-conservative substitutions may useamino acids between, rather than within, the defined groups listedabove. In one embodiment, a non-conservative mutation affects (a) thestructure of the peptide backbone in the area of the substitution (e.g.,proline for glycine) (b) the charge or hydrophobicity, or (c) the bulkof the side chain.

“Deletion” refers to modification to the polypeptide by removal of oneor more amino acids from the reference polypeptide. Deletions cancomprise removal of 1 or more amino acids, 2 or more amino acids, 5 ormore amino acids, 10 or more amino acids, 15 or more amino acids, or 20or more amino acids, up to 10% of the total number of amino acids, or upto 20% of the total number of amino acids making up the reference enzymewhile retaining enzymatic activity and/or retaining the improvedproperties of an engineered ketoreductase enzyme. Deletions can bedirected to the internal portions and/or terminal portions of thepolypeptide. In various embodiments, the deletion can comprise acontinuous segment or can be discontinuous.

“Insertion” refers to modification to the polypeptide by addition of oneor more amino acids from the reference polypeptide. In some embodiments,the improved engineered ketoreductase enzymes comprise insertions of oneor more amino acids to the naturally occurring ketoreductase polypeptideas well as insertions of one or more amino acids to other improvedketoreductase polypeptides. Insertions can be in the internal portionsof the polypeptide, or to the carboxy or amino terminus. Insertions asused herein include fusion proteins as is known in the art. Theinsertion can be a contiguous segment of amino acids or separated by oneor more of the amino acids in the naturally occurring polypeptide.

“Different from” or “differs from” with respect to a designatedreference sequence refers to difference of a given amino acid orpolynucleotide sequence when aligned to the reference sequence.Generally, the differences can be determined when the two sequences areoptimally aligned. Differences include insertions, deletions, orsubstitutions of amino acid residues in comparison to the referencesequence.

“Fragment” as used herein refers to a polypeptide that has anamino-terminal and/or carboxy-terminal deletion, but where the remainingamino acid sequence is identical to the corresponding positions in thesequence. Fragments can be at least 14 amino acids long, at least 20amino acids long, at least 50 amino acids long or longer, and up to 70%,80%, 90%, 95%, 98%, and 99% of the full-length ketoreductasepolypeptide.

“Isolated polypeptide” refers to a polypeptide which is substantiallyseparated from other contaminants that naturally accompany it, e.g.,protein, lipids, and polynucleotides. The term embraces polypeptideswhich have been removed or purified from their naturally-occurringenvironment or expression system (e.g., host cell or in vitrosynthesis). The improved ketoreductase enzymes may be present within acell, present in the cellular medium, or prepared in various forms, suchas lysates or isolated preparations. As such, in some embodiments, theimproved ketoreductase enzyme can be an isolated polypeptide.

“Substantially pure polypeptide” refers to a composition in which thepolypeptide species is the predominant species present (i.e., on a molaror weight basis it is more abundant than any other individualmacromolecular species in the composition), and is generally asubstantially purified composition when the object species comprises atleast about 50 percent of the macromolecular species present by mole or% weight. Generally, a substantially pure ketoreductase composition willcomprise about 60% or more, about 70% or more, about 80% or more, about90% or more, about 95% or more, and about 98% or more of allmacromolecular species by mole or % weight present in the composition.In some embodiments, the object species is purified to essentialhomogeneity (i.e., contaminant species cannot be detected in thecomposition by conventional detection methods) wherein the compositionconsists essentially of a single macromolecular species. Solventspecies, small molecules (<500 Daltons), and elemental ion species arenot considered macromolecular species. In some embodiments, the isolatedimproved ketoreductases polypeptide is a substantially pure polypeptidecomposition.

“Stringent hybridization” is used herein to refer to conditions underwhich nucleic acid hybrids are stable. As known to those of skill in theart, the stability of hybrids is reflected in the melting temperature(T_(m)) of the hybrids. In general, the stability of a hybrid is afunction of ion strength, temperature, G/C content, and the presence ofchaotropic agents. The T_(m) values for polynucleotides can becalculated using known methods for predicting melting temperatures (see,e.g., Baldino et al., Methods Enzymology 168:761-777; Bolton et al.,1962, Proc. Natl. Acad. Sci. USA 48:1390; Bresslauer et al., 1986, Proc.Natl. Acad. Sci USA 83:8893-8897; Freier et al., 1986, Proc. Natl. Acad.Sci USA 83:9373-9377; Kierzek et al., Biochemistry 25:7840-7846; Rychliket al., 1990, Nucleic Acids Res 18:6409-6412 (erratum, 1991, NucleicAcids Res 19:698); Sambrook et al., supra); Suggs et al., 1981, InDevelopmental Biology Using Purified Genes (Brown et al., eds.), pp.683-693, Academic Press; and Wetmur, 1991, Crit Rev Biochem Mol Biol26:227-259. All publications incorporate herein by reference). In someembodiments, the polynucleotide encodes the polypeptide disclosed hereinand hybridizes under defined conditions, such as moderately stringent orhighly stringent conditions, to the complement of a sequence encoding anengineered ketoreductase enzyme of the present disclosure.

“Hybridization stringency” relates to such washing conditions of nucleicacids. Generally, hybridization reactions are performed under conditionsof lower stringency, followed by washes of varying but higherstringency. The term “moderately stringent hybridization” refers toconditions that permit target-DNA to bind a complementary nucleic acidthat has about 60% identity, preferably about 75% identity, about 85%identity to the target DNA; with greater than about 90% identity totarget-polynucleotide. Exemplary moderately stringent conditions areconditions equivalent to hybridization in 50% formamide, 5× Denhart'ssolution, 5×SSPE, 0.2% SDS at 42° C., followed by washing in 0.2×SSPE,0.2% SDS, at 42° C. “High stringency hybridization” refers generally toconditions that are about 10° C. or less from the thermal meltingtemperature T_(m) as determined under the solution condition for adefined polynucleotide sequence. In some embodiments, a high stringencycondition refers to conditions that permit hybridization of only thosenucleic acid sequences that form stable hybrids in 0.018M NaCl at 65° C.(i.e., if a hybrid is not stable in 0.018M NaCl at 65° C., it will notbe stable under high stringency conditions, as contemplated herein).High stringency conditions can be provided, for example, byhybridization in conditions equivalent to 50% formamide, 5× Denhart'ssolution, 5×SSPE, 0.2% SDS at 42° C., followed by washing in 0.1×SSPE,and 0.1% SDS at 65° C. Other high stringency hybridization conditions,as well as moderately stringent conditions, are described in thereferences cited above.

“Heterologous” polynucleotide refers to any polynucleotide that isintroduced into a host cell by laboratory techniques, and includespolynucleotides that are removed from a host cell, subjected tolaboratory manipulation, and then reintroduced into a host cell.

“Codon optimized” refers to changes in the codons of the polynucleotideencoding a protein to those preferentially used in a particular organismsuch that the encoded protein is efficiently expressed in the organismof interest. Although the genetic code is degenerate in that most aminoacids are represented by several codons, called “synonyms” or“synonymous” codons, it is well known that codon usage by particularorganisms is nonrandom and biased towards particular codon triplets.This codon usage bias may be higher in reference to a given gene, genesof common function or ancestral origin, highly expressed proteins versuslow copy number proteins, and the aggregate protein coding regions of anorganism's genome. In some embodiments, the polynucleotides encoding theketoreductases enzymes may be codon optimized for optimal productionfrom the host organism selected for expression.

“Preferred, optimal, high codon usage bias codons” refersinterchangeably to codons that are used at higher frequency in theprotein coding regions than other codons that code for the same aminoacid. The preferred codons may be determined in relation to codon usagein a single gene, a set of genes of common function or origin, highlyexpressed genes, the codon frequency in the aggregate protein codingregions of the whole organism, codon frequency in the aggregate proteincoding regions of related organisms, or combinations thereof. Codonswhose frequency increases with the level of gene expression aretypically optimal codons for expression. A variety of methods are knownfor determining the codon frequency (e.g., codon usage, relativesynonymous codon usage) and codon preference in specific organisms,including multivariat analysis, for example, using cluster analysis orcorrespondence analysis, and the effective number of codons used in agene (see GCG CodonPreference, Genetics Computer Group WisconsinPackage; CodonW, John Peden, University of Nottingham; McInerney, J. O,1998, Bioinformatics 14:372-73; Stenico et al., 1994, Nucleic Acids Res.222437-46; Wright, F., 1990, Gene 87:23-29). Codon usage tables areavailable for a growing list of organisms (see for example, Wada et al.,1992, Nucleic Acids Res. 20:2111-2118; Nakamura et al., 2000, Nucl.Acids Res. 28:292; Duret, et al., supra; Henaut and Danchin,“Escherichia coli and Salmonella,” 1996, Neidhardt, et al. Eds., ASMPress, Washington D.C., p. 2047-2066. The data source for obtainingcodon usage may rely on any available nucleotide sequence capable ofcoding for a protein. These data sets include nucleic acid sequencesactually known to encode expressed proteins (e.g., complete proteincoding sequences-CDS), expressed sequence tags (ESTS), or predictedcoding regions of genomic sequences (see for example, Mount, D.,Bioinformatics: Sequence and Genome Analysis, Chapter 8, Cold SpringHarbor Laboratory Press, Cold Spring Harbor, N.Y., 2001; Uberbacher, E.C., 1996, Methods Enzymol. 266:259-281; Tiwari et al., 1997, Comput.Appl. Biosci. 13:263-270).

“Control sequence” is defined herein to include all components, whichare necessary or advantageous for the expression of a polypeptide of thepresent disclosure. Each control sequence may be native or foreign tothe nucleic acid sequence encoding the polypeptide. Such controlsequences include, but are not limited to, a leader, polyadenylationsequence, propeptide sequence, promoter, signal peptide sequence, andtranscription terminator. At a minimum, the control sequences include apromoter, and transcriptional and translational stop signals. Thecontrol sequences may be provided with linkers for the purpose ofintroducing specific restriction sites facilitating ligation of thecontrol sequences with the coding region of the nucleic acid sequenceencoding a polypeptide.

“Operably linked” is defined herein as a configuration in which acontrol sequence is appropriately placed at a position relative to thecoding sequence of the DNA sequence such that the control sequencedirects the expression of a polynucleotide and/or polypeptide.

“Promoter sequence” is a nucleic acid sequence that is recognized by ahost cell for expression of the coding region. The control sequence maycomprise an appropriate promoter sequence. The promoter sequencecontains transcriptional control sequences, which mediate the expressionof the polypeptide. The promoter may be any nucleic acid sequence whichshows transcriptional activity in the host cell of choice includingmutant, truncated, and hybrid promoters, and may be obtained from genesencoding extracellular or intracellular polypeptides either homologousor heterologous to the host cell.

“Cofactor regeneration system” refers to a set of reactants thatparticipate in a reaction that reduces the oxidized form of the cofactor(e.g., NADP+ to NADPH). Cofactors oxidized by theketoreductase-catalyzed reduction of the keto substrate are regeneratedin reduced form by the cofactor regeneration system. Cofactorregeneration systems comprise a stoichiometric reductant that is asource of reducing hydrogen equivalents and is capable of reducing theoxidized form of the cofactor. The cofactor regeneration system mayfurther comprise a catalyst, for example an enzyme catalyst thatcatalyzes the reduction of the oxidized form of the cofactor by thereductant. Cofactor regeneration systems to regenerate NADH or NADPHfrom NAD+ or NADP+, respectively, are known in the art and may be usedin the methods described herein.

6.2 Ketoreductase Enzymes

The present disclosure provides engineered ketoreductase (“KRED”)enzymes that are capable of stereoselectively reducing or converting thesubstrate 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to theproduct(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-oneand having an improved property when compared with thenaturally-occurring, wild-type KRED enzyme of L. kefir (SEQ ID NO:4), L.brevis (SEQ ID NO:2), or L. minor (SEQ ID NO: 158), or when comparedwith other engineered ketoreductase enzymes (e.g. that of SEQ ID NO:8).

The engineered ketoreductase (“KRED”) enzymes are also capable ofstereoselectively reducing or converting the compound1-(4-fluorophenyl)-3(R)-[3-oxo-3-(4-fluorophenyl)propyl]-4(S)-(4-hydroxyphenyl)-2-azetidinoneto the corresponding stereoisomeric alcohol product1-(4-fluorophenyl)-3(R)-[3(S)-hydroxy-3(4-fluorophenyl)-propyl)]-4(S)-(4-hydroxyphenyl)-2-azetidinoneand having an improved property when compared with thenaturally-occurring, wild-type KRED enzyme of L. kefir (SEQ ID NO:4), L.brevis (SEQ ID NO:2), or L. minor (SEQ ID NO:158) or when compared withother engineered ketoreductase enzymes (e.g. that of SEQ ID NO:8).

Enzyme properties for which improvement is desirable include, but arenot limited to, enzymatic activity, thermal stability, pH activityprofile, cofactor requirements, refractoriness to inhibitors (e.g.,product inhibition), sterospecificity, stereoselectivity, and solventstability. The improvements can relate to a single enzyme property, suchas enzymatic activity, or a combination of different enzyme properties,such as enzymatic activity and stereoselectivity. For the polypeptidesdescribed herein, the amino acid sequence of the ketoreductasepolypeptides have the requirement that: (1) the amino acid residuecorresponding to residue position 145 of SEQ ID NO:2, 4, or 158 isserine and (2) the amino acid residue corresponding to residue position190 of SEQ ID NO:2, 4, or 158 is cysteine.

In some embodiments, as noted above, the engineered ketoreductase withimproved enzyme activity is described with reference to Lactobacilluskefir ketoreductase of SEQ ID NO:4, Lactobacillus brevis ketoreductaseof SEQ ID NO:2, or Lactobacillus minor of SEQ ID NO:158. The amino acidresidue position is determined in both ketoreductases beginning from theinitiating methionine (M) residue (i.e., M represents residue position1), although it will be understood by the skilled artisan that thisinitiating methionine residue may be removed by biological processingmachinery, such as in a host cell or in vitro translation system, togenerate a mature protein lacking the initiating methionine residue. Theamino acid residue position at which a particular amino acid or aminoacid change is present is sometimes describe in terms “Xn”, or “positionn”, where n refers to the residue position. Where the amino acidresidues at the same residue position differ between the ketoreductases,the different residues are denoted by an “/” with the arrangement being,for example, “kefir residue/brevis residue/minor.” A substitutionmutation, which is a replacement of an amino acid residue in acorresponding residue of a reference sequence, for example the wildtypeketoreductases of SEQ ID NO:2, SEQ ID NO:4, or SEQ ID NO:158 with adifferent amino acid residue is denoted by the symbol “→”.

Herein, mutations are sometimes described as a mutation “to a” type ofamino acid. For example, residue 211 can be mutated “to a” basicresidue. But the use of the phrase “to a” does not exclude mutationsfrom one amino acid of a class to another amino acid of the same class.For example, residue 211 can be mutated from a lysine to an arginine.

The polynucleotide sequence encoding the naturally occurringketoreductase of Lactobacillus kefir and Lactobacillus brevis (alsoreferred to as “alcohol dehydrogenase” or “ADH”), and thus thecorresponding amino acid sequences, are available from Genbank accessionno. AAP94029 GI:33112056 for Lactobacillus kefir, Genbank accession no.CAD66648 GI:28400789 for Lactobacillus brevis, and U.S. Pat. Appl. No.20040265978 or SEQ ID NO:158 for Lactobacillus minor.

In some embodiments, the ketoreductase polypeptides herein can have anumber of modifications to the reference sequence (e.g., naturallyoccurring polypeptide or an engineered polypeptide) to result in animproved ketoreductase property. In such embodiments, the number ofmodifications to the amino acid sequence can comprise one or more aminoacids, 2 or more amino acids, 3 or more amino acids, 4 or more aminoacids, 5 or more amino acids, 6 or more amino acids, 8 or more aminoacids, 10 or more amino acids, 15 or more amino acids, or 20 or moreamino acids, up to 10% of the total number of amino acids, up to 20% ofthe total number of amino acids, or up to 30% of the total number ofamino acids of the reference enzyme sequence. In some embodiments, thenumber of modifications to the naturally occurring polypeptide or anengineered polypeptide that produces an improved ketoreductase propertymay comprise from about 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35or about 1-40 modifications of the reference sequence. The modificationscan comprise insertions, deletions, substitutions, or combinationsthereof.

In some embodiments, the modifications comprise amino acid substitutionsto the reference sequence. Substitutions that can produce an improvedketoreductase property may be at one or more amino acids, 2 or moreamino acids, 3 or more amino acids, 4 or more amino acids, 5 or moreamino acids, 6 or more amino acids, 8 or more amino acids, 10 or moreamino acids, or 20 or more amino acids, up to 10% of the total number ofamino acids, up to 20% of the total number of amino acids, or up to 30%of the total number of amino acids of the reference enzyme sequence. Insome embodiments, the number of substitutions to the naturally occurringpolypeptide or an engineered polypeptide that produces an improvedketoreductase property can comprise from about 1-2, 1-3, 1-4, 1-5, 1-6,1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22,1-24, 1-25, 1-30, 1-35 or about 1-40 amino acid substitutions of thereference sequence.

In some embodiments, the improved property, as compared to wild-type oranother engineered polypeptide, of the ketoreductase polypeptide is withrespect to an increase of its stereoselectivity i.e., herein, anincrease in the stereomeric excess of the product, for reducing orconverting the substrate 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to theproduct(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one.In some embodiments, the improved property of the ketoreductasepolypeptide is with respect to an increase in its ability to convert orreduce a greater percentage of the substrate to the product. In someembodiments, the improved property of the ketoreductase polypeptide iswith respect to an increase in its rate of conversion of the substrateto the product. This improvement in enzymatic activity can be manifestedby the ability to use less of the improved polypeptide as compared tothe wild-type or other reference sequence (for example, SEQ ID NO:8) toreduce or convert the same amount of product. In some embodiments, theimproved property of the ketoreductase polypeptide is with respect toits stability or thermostability. In some embodiments, the ketoreductasepolypeptide has more than one improved property.

In some embodiments, the ketoreductase polypeptide of the disclosure iscapable of converting the substrate 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to theproduct(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one,with a percent stereomeric excess of at least about 90% and at a ratethat is improved over the amino acid sequence of SEQ ID NO:8. Exemplarypolypeptides with such properties include, but are not limited to,polypeptides which comprise an amino acid sequence corresponding to SEQID NO: 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72,74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106,108, 110, 112, 114, 116, 118, 120, 122, 124, and 126. Because thereference polypeptide having the amino acid sequence of SEQ ID NO:8 iscapable of converting the substrate to the product at a rate (forexample, 4% of 1 g/L substrate converted to product in 24 hours withabout 5 g/L of the KRED) and with a steroselectivity (94% stereomericexcess) that is improved over wild-type (SEQ ID NO:4), the polypeptidesherein that are improved over SEQ ID NO:8 are also improved overwild-type.

In some embodiments, the ketoreductase polypeptide is capable ofconverting the substrate 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to theproduct(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one,with a percent stereomeric excess of at least about 99% and at a ratethat is at least about 5 times improved over a reference polypeptidehaving the amino acid sequence of SEQ ID NO: 8. Exemplary polypeptideswith such properties include, but are not limited to, polypeptides whichcomprise an amino acid sequence corresponding to SEQ ID NO: 42, 44, 46,50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84,86, 88, 90, 92, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116,118, 120, 122, 124, and 126.

In some embodiments, the ketoreductase polypeptide is capable ofconverting the substrate 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to theproduct(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one,with a percent stereomeric excess of at least about 99% and at a ratethat is at least about 120 times or more improved over a referencepolypeptide having the amino acid sequence of SEQ ID NO:8. Exemplarypolypeptides with such properties include, but are not limited to,polypeptides which comprise an amino acid sequence corresponding to SEQID NO: 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82,84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114,116, 118, 120, 122, 124, and 126.

In some embodiments, the ketoreductase polypeptide is capable ofconverting the substrate 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to theproduct(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one,with a percent stereomeric excess of at least about 99% and at a ratethat is at least about 3000 times or more improved over a referencepolypeptide having the amino acid sequence of SEQ ID NO:8. Exemplarypolypeptides with such properties include, but are not limited to,polypeptides which comprise an amino acid sequence corresponding to SEQID NO: 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104,106, 108, 110, 112, 114, 116, 118, 120, 122, 124, and 126.

In some embodiments, the ketoreductase polypeptide is capable ofconverting the substrate 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione to theproduct(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one,with a percent stereomeric excess of at least about 99% and at a ratethat is at least about 7000 times or more improved over a referencepolypeptide having the amino acid sequence of SEQ ID NO:8. Exemplarypolypeptides with such properties include, but are not limited to,polypeptides which comprise an amino acid sequence corresponding to SEQID NO: 102, 108, 120, 122, 124, and 126.

In some embodiments, the ketoreductase polypeptides of the disclosurecomprise highly stereoselective ketoreductase polypeptides that canreduce the substrate to the product in greater than about 99%, 99.1%,99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8% or 99.9% stereomericexcess. Exemplary ketoreductase polypeptides with such highstereoselectivity include, but are not limited to, the polypeptidescomprising the amino acid sequences corresponding to SEQ ID NO: 42, 44,46, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82,84, 86, 88, 90, 92, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116,118, 120, 122, 124, and 126.

Tables 2, 3 and 4 below provide a list of the SEQ ID NOs disclosedherein with associated activities. The sequences below are based on thewild-type L. kefir ketoreductase sequences (SEQ ID NO: 3 and 4) unlessotherwise specified. In tables below, each row lists two SEQ ID NOs,where the odd number refers to the nucleotide sequence that codes forthe amino acid sequence provided by the even number. The column listingthe number of mutations (i.e., residue changes) refers to the number ofamino acid substitutions as compared to the L. kefir KRED amino acidsequence of SEQ ID NO:4. Each Table is followed by a caption indicatingthe meaning of the symbols “+” “++” “+++” and “++++” in each context.

TABLE 2 Activity of Various KREDs SEQ ID Residue Changes Relative toNumber of Changes NO: SEQ ID NO: 4 Relative to L Kefir Conversion^(a) %DE^(b)  5/6 Y190C; 1 + −  7/8 G7S; R108H; G117S; E145S; 8 +++ ++ N157T;Y190C; K211R; I223V  9/10 F147L; Y190P; V196L 3 + + 13/14 H40R; A94G;S96V; E145F; 10 + ++ F147M; Y190P; V196L; L199W; I226V; Y249W 27/28E145A; F147L; Y190C 3 +++ ++ 29/30 F147L; L153G; Y190P 3 +++ − 31/32F147L; Y190P 2 ++ − 33/34 E145S; F147L; Y190P 3 +++ + 35/36 E145Q;F147L; Y190A 3 ++ − 37/38 F147L; Y190P; K211L 3 ++ − 39/40 F147L; L153Q;Y190P 3 +++ − ^(a)- + indicates <10% conversion of substrate to product;++ indicates 10-60% conversion; +++ indicates >60% conversion ^(b)- −indicates R selectivity; + indicates <50% S,S-diastereomeric product; ++indicates >50% S,S-diastereomeric product

The following Table 3 and Table 4 show the activity profiles of variousketoreductases.

TABLE 3 List of Sequences and Corresponding Activity Improvement Numberof Changes SEQ Relative to the L. kefir ID NO Residue Changes (SEQ IDNO: 4) % Conversion^(a) % DE^(b)   7/8 G7S; R108H; G117S; E145S; 8 + +N157T; Y190C; K211R; I223V 11/12 A94G; S96V; E145L; L153T; 8 + + Y190P;V196L; I226V; Y249W; 15/16 H40R; A94G; S96V; E145F; 10 + + F147M; Y190P;V196L; M206F; I226V; Y249W 17/18 A94G; S96V; E145F; F147M; 9 + ++ L153T;Y190P; V196L; I226V; Y249W 19/20 A94G; S96V; E145F; F147M; 11 + ++L153T; Y190P; L195M; V196L; L199Y; I226V; Y249W 21/22 A94G; S96V; E145F;F147M; 10 + ++ T152S; L153T; Y190P; V196L; I226V; Y249W 23/24 A94G;S96V; E145F; F147M; 11 + ++ T152S; Y190P; L195M; V196L; M206F; I226V;Y249W 25/26 H40R; A94G; S96V; E145F; 10 + ++ F147M; L153T; Y190P; V196L;I226V; Y249W 41/42 G7S; A94G; R108H; G117S; 9 ++ + E145S; N157T; Y190C;K211R; I223V 43/44 G7S; S96Q; R108H; G117S; 9 ++ ++ E145S; N157T; Y190C;K211R; I223V 45/46 G7S; R108H; G117S; E145S; 9 ++ ++ N157T; Y190C;L199D; K211R; I223V 47/48 G7S; R108H; G117S; E145S; 9 ++ + N157T; Y190C;A202G; K211R; I223V 49/50 G7S; R108H; V113A; G117S; 10 ++ ++ E145S;N157T; Y190C; L199D; K211R; I223V 51/52 G7S; R108H; G117S; E145S; 10 +++++ T152K; N157T; Y190C; L199D; K211R; I223V 53/54 G7S; R108H; G117S;E145S; 10 +++ ++ T152M; N157T; Y190C; L199D; K211R; I223V 55/56 G7S;A945; 596Q; R108H; 11 +++ ++ G117S; E145S; N157T; Y190C; L199D; K211R;I223V 57/58 G7S; R108H; G117S; E145S; 10 +++ ++ N157T; Y190C; P194Q;L199D; K211R; I223V 59/60 G7S; A945; S96Q; R108H; 12 +++ ++ G117S;E145S; T152K; N157T; Y190C; L199D; K211R; I223V 61/62 G7S; A94S; S96Q;R108H; 12 +++ ++ G117S; E145S; T152M; N157T; Y190C; L199D; K211R; I223V;63/64 G7S; R108H; G117S; E145S; 11 +++ ++ F147L; T152M; N157T; Y190C;L199D; K211R; I223V; 65/66 G7S; S96N; R108H; G117S; 11 +++ ++ E145S;T152M; N157T; Y190C; L199D; K211R; I223V 67/68 G7S; R108H; G117S; E145S;11 +++ ++ T152M; N157T; Y190C; P194R; L199D; K211R; I223V 69/70 G7S;S96Q; R108H; G117S; 11 +++ ++ E145S; T152M; N157T; Y190C; L199D; K211R;I223V; 71/72 G7S; S96Q; R108H; G117S; 12 +++ ++ E145S; T152M; N157T;Y190C; P194R; L199D; K211R; I223V 73/74 G7S; S96T; R108H; G117S; 12 +++++ E145S; T152M; N157T; Y190C; P194R; L199D; K211R; I223V 75/76 G7S;D25T; D75N; S96Q; 14 ++++ ++ R108H; G117S; E145S; T152M; N157T; Y190C;P194R; L199D; K211R; I223V 77/78 G7S; S96Q; R108H; G117S; 10 ++++ ++E145S; T152M; Y190C; L199D; K211R; I223V 79/80 G7S; H40R; S96Q; R108H;12 +++ ++ G117S; E145S; T152M; N157T; Y190C; L199D; K211R; I223V; 81/82G7S; D25T; V95L; S96Q; 14 ++++ ++ R108H; G117S; E145S; T152M; L176V;Y190C; D198E; L199D; K211R; I223V 83/84 G7S; D25T; V95L; S96Q; 14 ++++++ R108H; G117S; E145S; T152M; L176V; Y190C; D197E; L199D; K211R; I223V89/90 G7S; S96Q; E145S; T152M; 7 ++++ ++ Y190C; L199D; K211R 93/94 G7S;G53D; S96Q; R108H; 12 ++++ ++ G117S; E145S; T152M; V1631; Y190C; L199D;K211R; I223V ^(a)- + indicates <50 mg product/g enzyme; ++ 50-1000 mgproduct/g enzyme; +++ indicates >1000 mg product/g enzyme ^(b)- +indicates 90-99% S,S-diastereomeric product; ++ indicates > 99%S,S-diastereomeric product

TABLE 4 List of Sequences and Corresponding Activity Improvement Numberof Changes SEQ ID Relative to the L. kefir NO: Residue Changes (SEQ IDNO: 4) % Conversion^(a) % DE^(b)  75/76 G7S; D25T; D75N; S96Q; 14 ++R108H; G117S; E145S; T152M; N157T; Y190C; P194R; L199D; K211R; I223V 81/82 G7S; D25T; V95L; S96Q; 14 ++ ++ R108H; G117S; E145S; T152M;L176V; Y190C; D198E; L199D; K211R; I223V  83/84 G7S; D25T; V95L; S96Q;14 ++ ++ R108H; G117S; E145S; T152M; L176V; Y190C; D197E; L199D; K211R;I223V;  85/86 G7S; D25T; V95M; S96Q; 14 ++ ++ R108H; G117S; E145S;T152M; L176V; Y190C; P194R; L199D; K211R; I223V  87/88 G7S; S96Q; E145S;T152M; 8 ++ ++ Y190C; L199D; K211R; I223V  89/90 G7S; S96Q; E145S;T152M; 7 ++ ++ Y190C; L199D; K211R;  91/92 G7S; S96Q; R108H; E145S; 9 ++++ T152M; Y190C; L199D; K211R; I223V;  93/94 G7S; G53D; S96Q; R108H; 12++ ++ G117S; E145S; T152M; V163I; Y190C; L199D; K211R; I223V  95/96 G7S;V95L; S96Q; R108H; 11 ++ ++ G117S; E145S; T152M; Y190C; L199D; K211R;I223V;  97/98 G7S; S96Q; R108N; G117S; 10 ++ ++ E145S; T152M; Y190C;L199D; K211R; I223V  99/100 G7S; S96Q; D101G; R108H; 12 ++ ++ G117S;E145S; F147L; T152M; Y190C; L199D; K211R; I223V 101/102 G7S; S96Q;R108H; L111M; 11 +++ ++ G117S; E145S; T152M; Y190C; L199D; K211R; I223V103/104 G7S; S96Q; R108H; G117S; 11 ++ ++ E145S; T152M; Y190C; L199D;K211R; I223V; T250I; 105/106 G7S; E29G; S96Q; D101N; 13 ++ ++ R108H;G117S; E145S; T152M; Y190C; L199D; E200P; K211R; I223V; 107/108 G7S;L17Q; S96Q; R108H; 11 +++ ++ G117S; E145S; T152M; Y190C; L199D; K211R;I223V 109/110 G7S; S96Q; R108H; S112D; 12 ++ ++ G117S; E145S; T152M;Y190C; D198G; L199D; K211R; I223V 111/112 G7S; S96Q; R108S; G117S; 10 ++++ E145S; T152M; Y190C; L199D; K211R; I223V 113/114 D3N; G7S; L17Q;D42G; S96Q; 16 ++ ++ R108H; Q127R; E145S; T152M; L176V; Y190C; P194R;L199D; E200P; K211R; I223V 115/116 D3N; G7S; L17Q; L21F; S96Q; 14 ++ ++R108H; E145S; F147L; T152M; L176V; Y190C; L199D; K211R; I223V; 117/118D3N; G7S; L17Q; E29A; D42G; 18 ++ ++ S96Q; E105G; R108H; G117S; E145S;T152M; Y190C; D197V; D198K; L199D; E200P; K211R; I223V; 119/120 G7S;L17Q; D42G; S96Q; 14 +++ ++ R108H; G117S; E145S; T152M; V163I; Y190C;D198K; L199D; K211R; I223V 121/122 G7S; L17Q; E29A; S96Q; 14 +++ ++R108H; G117S; E145S; T152M; V163I; Y190C; D198K; L199D; E200P; K211R123/124 G7S; L17Q; D42G; S96Q; 16 +++ ++ R108H; G117S; E145S; F147L;T152M; V163I; L176V; Y190C; D198K; L199D; K211R; I223V 125/126 G7S;L17Q; E29A; S96Q; 17 +++ ++ R108H; G117S; E145S; F147L; T152M; V163I;L176V; Y190C; D198K; L199D; E200P; K211R; I223V ^(a)- + indicates <1 gproduct/g enzyme/hr; ++ indicates 1-2.5 g product/g enzyme/hr; and +++indicates >2.5 g product/g enzyme/hr ^(b)- + indicates 90-99%S,S-diastereomeric product; ++ indicates > 99% S,S-diastereomericproduct

In some embodiments, the ketoreductase polypeptides herein comprises anamino acid sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%,91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical as compared areference sequence comprising the sequence of SEQ ID NO:128, 130, or160, with the proviso that the ketoreductase polypeptide comprises anamino acid sequence in which the amino acid residue corresponding toresidue position 145 is a polar residue, and the amino acid residuecorresponding to residue position 190 is a cysteine. The polypeptides ofSEQ ID NO: 128, 130, and 160 are variants of the L. brevis, L. kefir,and L. minor ketoreductases, respectively, each having the sequencesubstitutions: E145S and Y190C. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence in which the amino acidresidue corresponding to residue position 145 is serine, and the aminoacid residue corresponding to position 190 is cysteine. In someembodiments, the ketoreductase polypeptides can have one or more residuedifferences at other amino acid residues as compared to the referencesequence. The differences can include substitutions, deletions, andinsertions as compared to any of the reference sequences of SEQ IDNO:128, 130, or 160. The differences can be non-conservativesubstitutions, conservative substitutions, or a combination ofnon-conservative and conservative substitutions. In some embodiments,these ketoreductase polypeptides can have optionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 differences at other aminoacid residues. In some embodiments, the number of differences with thereference sequence can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15,16, 18, 20, 22, 24, 26, 30, 35 or about 40 differences at other aminoacid residues. In some embodiments, the differences compriseconservative mutations as compared to the reference sequence.

In some embodiments, an improved ketoreductase polypeptide comprises anamino acid sequence based on the sequence formulas as laid out in SEQ IDNO:161, 162, or 163, or a region thereof, such as residues 90-211. Thesequence formula of SEQ ID NO:161 is based on the amino acid sequence ofthe Lactobacillus brevis ketoreductase, as represented by SEQ ID NO:2.The sequence formula of SEQ ID NO:162 is based on the amino acidsequence of the Lactobacillus kefir ketoreductase, as represented by SEQID NO:4. The sequence formula of SEQ ID NO:163 is based on the aminoacid sequence of the Lactobacillus minor ketoreductase, as representedby SEQ ID NO:158. In some embodiments, the ketoreductase polypeptidebased on the sequence formulas of SEQ ID NO:161, 162, or 163 cancomprise an amino acid sequence that is at least about 85%, 86%, 87%,88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identicalto SEQ ID NO:128, 130, or 160, with the proviso that the ketoreductasepolypeptide has an amino acid sequence in which the residuecorresponding to X145 is a polar residue, particularly serine, and theamino acid residue corresponding to X190 is a cysteine.

In some embodiments, an improved ketoreductase polypeptide comprises anamino acid sequence based on the sequence formula of SEQ ID NO:161, 162or 163 in which the amino acid sequence has the specified features forresidues X145 and X190 as described herein, and wherein the polypeptidecan further include one or more features selected from the following:residue corresponding to X3 is an acidic, a polar, or hydrophilicresidue; residue corresponding to X7 is a non-polar or polar residue;residue corresponding to X17 is a non-polar, aliphatic or polar residue;residue corresponding to X21 is a non-polar, aromatic, or hydrophobicresidue; residue corresponding to X25 is an acidic, non-polar or polarresidue; residue corresponding to X29 is an acidic, aliphatic ornon-polar residue; residue corresponding to X40 is a constrained, basic,or hydrophilic residue; residue corresponding to X42 is an acidic or anon-polar residue; residue corresponding to X53 is a non-polar or anacidic residue; residue corresponding to X75 is an acidic or polarresidue; residue corresponding to X94 is a non-polar or a polar residue;residue corresponding to X95 is a non-polar or aliphatic residue;residue corresponding to X96 is a polar residue; residue correspondingto X101 is an acidic, non-polar, or a polar residue; residuecorresponding to X105 is an acidic or non-polar residue; residuecorresponding to X108 is a hydrophilic, polar or constrained residue;residue corresponding to X111 is a non-polar or aliphatic residue;residue corresponding to X112 is an acidic or polar residue; residuecorresponding to X113 is a non-polar or aliphatic residue; residuecorresponding to X117 is a non-polar or polar residue; residuecorresponding to X127 is a basic or polar residue; residue correspondingto X147 is a non-polar, aromatic, or hydrophobic residue; residuecorresponding to X152 is a non-polar, basic residue, or hydrophilicresidue; residue corresponding to X157 is a polar residue; residuecorresponding to X163 is a non-polar or aliphatic residue; residuecorresponding to X176 is a non-polar or aliphatic residue; residuecorresponding to X194 is a constrained, basic, or polar residue; residuecorresponding to X197 is a hydrophilic, acidic, basic, aliphatic ornon-polar residue; residue corresponding to X198 is an acidic, basic,hydrophilic, or non-polar residue; residue corresponding to X199 is anacidic, aliphatic, or non-polar residue; residue corresponding to X200is an acidic or constrained residue; residue corresponding to X202 is anon-polar or aliphatic residue; residue corresponding to X206 is anon-polar, aromatic, or hydrophobic residue; residue corresponding toX211 is a basic residue; residue corresponding to X223 is a non-polar oraliphatic residue; and residue corresponding to X250 is a polar or anon-polar residue. In some embodiments, the polypeptides comprising anamino acid sequence that corresponds to the sequence formulas providedin SEQ ID NO:161, 162 or 163 (or region thereof) can have additionallyone or more of the residues not specified by an X to be mutated. In someembodiments, the mutations can be 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 mutations at other amino acid residues notdefined by X above. In some embodiments, the number of mutations can be1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26,30, 35 or about 40 mutations at other amino acid residues. In someembodiments, the mutations comprise conservative mutations.

In some of the embodiments above, the ketoreductase polypeptidescomprising an amino acid sequence that corresponds to the sequenceformula as laid out in SEQ ID NO:161, 162 or 163 (or region thereof) canhave one or more conservatively mutations as compared to the referencesequence of SEQ ID NO:128, 130, or 160. Exemplary conservative mutationsinclude amino acid replacements such as, but not limited to: thereplacement of residue corresponding to X95 (valine) with anothernon-polar amino acid, e.g., alanine, leucine, isoleucine, glycine, ormethionine; the replacement of residue corresponding to X96 (serine)with another polar amino acid, e.g., asparagine, glutamine, orthreonine; the replacement of residue corresponding to X111 (leucine)with another non-polar amino acid, e.g., alanine, leucine, isoleucine,glycine, or methionine; the replacement of residue corresponding to X113(valine) with another aliphatic amino acid, e.g., alanine, leucine, orisoleucine; the replacement of residue corresponding to X157(asparagine) with another polar amino acid, e.g., glutamine, serine, orthreonine; the replacement of residue corresponding to X163 (valine)with another aliphatic amino acid, e.g., alanine, leucine, orisoleucine; the replacement of residue corresponding to X176 (leucine)with another aliphatic amino acid, e.g., alanine, valine, andisoleucine; the replacement of residue corresponding to X202 (alanine)with another non-polar amino acid, e.g., alanine, leucine, isoleucine,glycine, or methionine; the replacement of residue corresponding to X211(lysine) with another basic amino acid, e.g., arginine; the replacementof residue corresponding to X223 (isoleucine) with another aliphaticamino acid, e.g., alanine, leucine, or valine.

In some embodiments, an improved ketoreductase polypeptide comprises anamino acid sequence based on the sequence formula of SEQ ID NO:161, 162or 163 in which the amino acid sequence has the specified features forresidues X145 and X190 as described herein, and wherein the polypeptidecan further include one or more features selected from the following:residue corresponding to X3 is aspartic acid, glutamic acid, serine,threonine, asparagine, or glutamine, particularly asparagine; residuecorresponding to X7 is glycine, methionine, alanine, valine, leucine,isoleucine, serine, threonine, asparagine, or glutamine, particularlyserine; residue corresponding to X17 is glycine, methionine, alanine,valine, leucine, isoleucine, serine, threonine, asparagine, orglutamine, particularly glutamine; residue corresponding to X21 isglycine, methionine, alanine, valine, leucine, isoleucine, tyrosine,phenylalanine, or tryptophan, particularly phenylalanine; residuecorresponding to X25 is aspartic acid, glutamic acid, serine, threonine,asparagine, glutamine, glycine, methionine, alanine, valine, leucine,isoleucine, particularly threonine; residue corresponding to X29 isaspartic acid, glutamine acid, glycine, methionine, alanine, valine,leucine, or isoleucine, particularly glycine or alanine; residuecorresponding to X40 is histidine, lysine, arginine, serine, threonine,asparagine, or glutamine, particularly arginine; residue correspondingto X42 is aspartic acid, glutamic acid, glycine, methionine, alanine,valine, leucine, or isoleucine, particularly glycine; residuecorresponding to X53 is glycine, methionine, alanine, valine, leucine,isoleucine, aspartic acid, glutamic acid, particularly aspartic acid;residue corresponding to X75 is aspartic acid, glutamic acid, serine,threonine, asparagine, or glutamine, particularly arginine; residuecorresponding to X94 is glycine, methionine, alanine, valine, leucine,isoleucine, serine, threonine, asparagine, or glutamine, particularlyasparagine, glycine, or serine; residue corresponding to X95 is aglycine, methionine, alanine, valine, leucine, or isoleucine,particularly leucine or methionine; residue corresponding to X96 isserine, threonine, asparagine, glutamine, particularly glutamine,asparagine, or threonine; residue; residue corresponding to X101 isaspartic acid, glutamic acid, serine, threonine, asparagine, glutamine,or glycine, methionine, alanine, valine, leucine, or isoleucine,particularly glycine or asparagine; residue corresponding to X105 isglutamic acid, aspartic acid, glycine, methionine, alanine, valine,leucine, isoleucine, particularly glycine; residue corresponding to X108arginine, lysine, serine, threonine, asparagine, glutamine, histidine,particularly histidine or serine; residue corresponding to X111 isglycine, methionine, alanine, valine, leucine, or isoleucine,particularly methionine; or aliphatic residue; residue corresponding toX112 is aspartic acid, glutamic acid, serine, threonine, asparagine,glutamine, particularly aspartic acid; residue corresponding to X113 isan glycine, methionine, alanine, valine, leucine, isoleucine,particularly alanine; residue corresponding to X117 is glycine,methionine, alanine, valine, leucine, isoleucine, serine, threonine,asparagine, or glutamine, particularly serine; residue corresponding toX127 is lysine, arginine, serine, threonine, asparagine, or glutamine,particularly arginine; residue corresponding to X147 is glycine,methionine, alanine, valine, leucine, isoleucine, tyrosine,phenylalanine, tryptophan, particularly leucine; residue correspondingto X152 is glycine, methionine, valine, leucine, isoleucine, arginine,lysine, serine threonine, asparagine, or glutamine, particularlymethionine or lysine; residue corresponding to X157 is a serine,threonine, asparagine, and glutamine, particularly threonine; residuecorresponding to X163 is a glycine, methionine, alanine, valine,leucine, or isoleucine, particularly isoleucine; residue correspondingto X176 is glycine, methionine, alanine, valine, leucine, or isoleucine,particularly valine; residue corresponding to X194 is proline, arginine,lysine, serine, threonine, asparagine, glutamine, particularly arginineor glutamine; residue corresponding to X197 is aspartic acid, glutamicacid, arginine, lysine, serine, threonine, asparagine, glutamine,glycine, methionine, alanine, valine, leucine, isoleucine, particularlyvaline or glutamic acid; residue corresponding to X198 is aspartic acid,glutamic acid, arginine, lysine, serine, threonine, asparagine,glutamine, glycine, methionine, alanine, valine, leucine, or isoleucine,particularly glycine, glutamic acid, or lysine; residue corresponding toX199 is an aspartic acid, glutamic acid, glycine, methionine, alanine,valine, leucine, or isoleucine, particularly aspartic acid; residuecorresponding to X200 is an aspartic acid, glutamic acid, or proline,particularly proline; residue corresponding to X202 is glycine,methionine, alanine, valine, leucine, isoleucine, particularly glycine;residue corresponding to X206 is a glycine, methionine, alanine, valine,leucine, isoleucine, tyrosine, phenylalanine, tryptophan, particularlyglycine; residue corresponding to X211 is a arginine or lysine; residuecorresponding to X223 is glycine, methionine, alanine, valine, leucine,or isoleucine, particularly valine; and residue corresponding to X250 isserine, threonine, asparagine, glutamine, glycine, methionine, alanine,valine, leucine, isoleucine, particularly isoleucine. In someembodiments, the polypeptides comprising an amino acid sequence thatcorresponds to the sequence formulas of SEQ ID NO:161, 162 or 163 (orregion thereof) can have additionally one or more of the residues notspecified by an X to be mutated as compared to the reference sequence ofSEQ ID NO:128, 130, or 160. In some embodiments, the mutations can be1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15,1-16, 1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 mutationsat other amino acid residues not defined by X above. In someembodiments, the number of mutations can be 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40 mutationsat other amino acid residues. In some embodiments, the mutationscomprise conservative mutations.

In some embodiments, an improved ketoreductase polypeptide comprises anamino acid sequence based on the sequence formula of SEQ ID NO:161, 162or 163 in which the amino acid sequence has the specified features forresidues X145 and X190 as described herein, and wherein the polypeptidecan further include one or more or at least all of the features selectedfrom the following: the residue corresponding to X7 is a non-polar orpolar residue; residue corresponding to X108 is a hydrophilic, polar orconstrained residue; residue corresponding to X117 is a non-polar or apolar residue; residue corresponding to X152 is a non-polar, basic, orhydrophilic residue; and residue corresponding to X199 is an acidic,aliphatic, or non-polar residue. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, an improved ketoreductase polypeptide comprises anamino acid sequence based on the sequence formula of SEQ ID NO:161, 162or 163 in which the amino acid sequence has the specified features forresidues X145 and X190 as described herein, and wherein the polypeptidecan further include one or more or at least all of the features selectedfrom the following: the residue corresponding to X7 is glycine,methionine, alanine, valine, leucine, isoleucine, serine, threonine,asparagine, or glutamine, particularly serine; residue corresponding toX108 is arginine, lysine, serine, threonine, asparagine, glutamine,histidine, particularly histidine or serine; residue corresponding toX117 is glycine, methionine, alanine, valine, leucine, isoleucine,serine, threonine, asparagine, or glutamine, particularly serine;residue corresponding to X152 is glycine, methionine, valine, leucine,isoleucine, arginine, lysine, serine threonine, asparagine, orglutamine, particularly methionine or lysine; and residue correspondingto X199 is aspartic acid, glutamic acid, glycine, methionine, alanine,valine, leucine, or isoleucine, particularly aspartic acid. In someembodiments, the ketoreductase polypeptides can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residuedifferences at other amino acid residues as compared to the referencesequence of SEQ ID NO:128, 130, or 160. In some embodiments, the numberof differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with at least the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity as compared to a reference sequence based on SEQ ID NO:128,130, or 160 with the preceding features.

In some embodiments, an improved ketoreductase polypeptide comprises anamino acid sequence based on the sequence formula of SEQ ID NO:161, 162or 163 in which the amino acid sequence has the specified features forresidues X145 and X190 as described herein, and wherein the polypeptidecan further include one or more or at least all of the features selectedfrom the following: residue corresponding to X3 is an acidic, polar, orhydrophilic residue; residue corresponding to X17 is a non-polar,aliphatic or polar residue; residue corresponding to X25 is an acidic,non-polar or polar residue; residue corresponding to X42 is an acidic ornon-polar residue; residue corresponding to X94 is a non-polar or apolar residue; residue corresponding to X194 is a constrained, basic, orpolar residue; residue corresponding to X198 is an acidic, basic,hydrophilic, or non-polar residue; and residue corresponding to X200 isan acidic or a constrained residue. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, an improved ketoreductase polypeptide comprises anamino acid sequence based on the sequence formula of SEQ ID NO:161, 162or 163 in which the amino acid sequence has the specified features forresidues X145 and X190 as described herein, and wherein the polypeptidecan further include one or more or at least all of the features selectedfrom the following: residue corresponding to X3 is aspartic acid,glutamic acid, serine, threonine, asparagine, or glutamine, particularlyasparagine; residue corresponding to X17 is glycine, methionine,alanine, valine, leucine, isoleucine, serine, threonine, asparagine, orglutamine, particularly glutamine; residue corresponding to X25 isaspartic acid, glutamic acid, serine, threonine, asparagine, glutamine,glycine, methionine, alanine, valine, leucine, isoleucine, particularlythreonine; residue corresponding to X42 is aspartic acid, glutamic acid,glycine, methionine, alanine, valine, leucine, or isoleucine,particularly glycine; residue corresponding to X94 is glycine,methionine, alanine, valine, leucine, isoleucine, serine, threonine,asparagine, or glutamine, particularly asparagine, glycine, or serine;residue corresponding to X194 is proline, arginine, lysine, serine,threonine, asparagine, glutamine, particularly arginine or glutamine;residue corresponding to X198 is aspartic acid, glutamic acid, arginine,lysine, serine, threonine, asparagine, glutamine, glycine, methionine,alanine, valine, leucine, or isoleucine, particularly glycine, glutamicacid, or lysine; residue corresponding to X200 is aspartic acid,glutamic acid, or proline, particularly proline. In some embodiments,the ketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, an improved ketoreductase polypeptide comprises anamino acid sequence based on the sequence formula of SEQ ID NO:161, 162or 163 in which the amino acid sequence has the specified features forresidues X145 and X190 as described herein, and wherein the polypeptidecan further include one or more or at least all of the features selectedfrom the following: residue corresponding to X3 is an acidic, polar, orhydrophilic residue; residue corresponding to X7 is a non-polar or polarresidue; residue corresponding to X17 is a non-polar, aliphatic or polarresidue; residue corresponding to X25 is an acidic, non-polar or polarresidue; residue corresponding to X42 is an acidic or non-polar residue;residue corresponding to X94 is a non-polar or a polar residue; residuecorresponding to X108 is a hydrophilic, polar or constrained residue;residue corresponding to X117 is a non-polar or a polar residue; residuecorresponding to X152 is a non-polar, basic, or hydrophilic residue;residue corresponding to X194 is a constrained, basic, or polar residue;residue corresponding to X198 is an acidic, basic, hydrophilic, ornon-polar residue; residue corresponding to X199 is an acidic,aliphatic, or non-polar residue; residue corresponding to X200 is anacidic or constrained residue. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, an improved ketoreductase polypeptide comprises anamino acid sequence based on the sequence formula of SEQ ID NO:161, 162or 163 in which the amino acid sequence has the specified features forresidues X145 and X190 as described herein, and wherein the polypeptidecan further include one or more or at least all of the features selectedfrom the following: residue corresponding to X3 is aspartic acid,glutamic acid, serine, threonine, asparagine, or glutamine, particularlyasparagine; residue corresponding to X7 is glycine, methionine, alanine,valine, leucine, isoleucine, serine, threonine, asparagine, orglutamine, particularly serine; residue corresponding to X17 is glycine,methionine, alanine, valine, leucine, isoleucine, serine, threonine,asparagine, or glutamine, particularly glutamine; residue correspondingto X25 is aspartic acid, glutamic acid, serine, threonine, asparagine,glutamine, glycine, methionine, alanine, valine, leucine, isoleucine,particularly threonine; residue corresponding to X42 is aspartic acid,glutamic acid, glycine, methionine, alanine, valine, leucine, orisoleucine, particularly glycine; residue corresponding to X94 isglycine, methionine, alanine, valine, leucine, isoleucine, serine,threonine, asparagine, or glutamine, particularly asparagine, glycine,or serine; residue corresponding to X108 is arginine, lysine, serine,threonine, asparagine, glutamine, histidine, particularly histidine orserine; residue corresponding to X117 is glycine, methionine, alanine,valine, leucine, isoleucine, serine, threonine, asparagine, orglutamine, particularly serine; residue corresponding to X152 isglycine, methionine, valine, leucine, isoleucine, arginine, lysine,serine threonine, asparagine, or glutamine, particularly methionine orlysine; residue corresponding to X194 is proline, arginine, lysine,serine, threonine, asparagine, glutamine, particularly arginine orglutamine; residue corresponding to X198 is aspartic acid, glutamicacid, arginine, lysine, serine, threonine, asparagine, glutamine,glycine, methionine, alanine, valine, leucine, or isoleucine,particularly glycine; residue corresponding to X199 is an aspartic acid,glutamic acid, glycine, methionine, alanine, valine, leucine, orisoleucine, particularly aspartic acid; residue corresponding to X200 isaspartic acid, glutamic acid, or proline, particularly proline. In someembodiments, the ketoreductase polypeptides can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residuedifferences at other amino acid residues as compared to the referencesequence of SEQ ID NO:128, 130, or 160. In some embodiments, the numberof differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with at least the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity as compared to a reference sequence based on SEQ ID NO:128,130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X3 is an acidic, a polar, or hydrophilicresidue, particularly asparagine. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X7 is a non-polar or polar residue,particularly serine. In some embodiments, the ketoreductase polypeptidescan have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35or about 1-40 residue differences at other amino acid residues ascompared to the reference sequence of SEQ ID NO:128, 130, or 160. Insome embodiments, the number of differences can be 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40residue differences at other amino acid residues. In some embodiments,the differences comprise conservative mutations. In some embodiments,the ketoreductase polypeptide comprises an amino acid sequence with atleast the preceding features, and wherein the amino acid sequence has atleast 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%,98%, or 99% identity as compared to a reference sequence based on SEQ IDNO:128, 130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X17 is a non-polar, aliphatic or polar residue,particularly glutamine. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X21 is a non-polar, aromatic, or hydrophobicresidue, particularly phenylalanine. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X25 is an acidic, non-polar or polar residue,particularly threonine or serine. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X29 is an acidic, aliphatic or non-polarresidue, particularly alanine or glycine. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, have at leastthe following features: amino acid residue corresponding to X145 is apolar residue, particularly serine; amino acid residue corresponding toX190 is a cysteine; and amino acid residue corresponding to X40 is aconstrained, basic, or hydrophilic residue, particularly arginine. Insome embodiments, the ketoreductase polypeptides can have additionally1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15,1-16, 1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residuedifferences at other amino acid residues as compared to the referencesequence of SEQ ID NO:128, 130, or 160. In some embodiments, the numberof differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with at least the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity as compared to a reference sequence based on SEQ ID NO:128,130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X42 is an acidic or a non-polar residue,particularly glycine. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X53 is a non-polar or an acidic residue,particularly aspartic acid. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X75 is an acidic or polar residue, particularlyasparagine. In some embodiments, the ketoreductase polypeptides can haveadditionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40residue differences at other amino acid residues as compared to thereference sequence of SEQ ID NO:128, 130, or 160. In some embodiments,the number of differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40 residue differencesat other amino acid residues. In some embodiments, the differencescomprise conservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with at least the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity as compared to a reference sequence based on SEQ ID NO:128,130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X94 is a non-polar or a polar residue,particularly glycine, serine, or asparagine. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162, or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and the aminoacid residue corresponding to X95 is a non-polar or aliphatic residue,particularly leucine or methionine. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:128,130, or 160, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidues corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and the aminoacid residue corresponding to X96 is a polar residue, particularlythreonine, asparagine or glutamine. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X101 is an acidic, non-polar, or a polarresidue, particularly asparagine or glycine. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X105 is an acidic or non-polar residue,particularly glycine. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X108 is a hydrophilic, polar or constrainedresidue, particularly histidine, serine or asparagine. In someembodiments, the ketoreductase polypeptides can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residuedifferences at other amino acid residues as compared to the referencesequence of SEQ ID NO:128, 130, or 160. In some embodiments, the numberof differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with at least the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity as compared to a reference sequence based on SEQ ID NO:128,130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X111 is a non-polar or aliphatic residue,particularly methionine. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X112 is an acidic or polar residue,particularly aspartic acid. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidues corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X113 is a non-polar or aliphatic residue,particularly alanine. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X117 is a non-polar or a polar residue,particularly serine. In some embodiments, the ketoreductase polypeptidescan have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35or about 1-40 residue differences at other amino acid residues ascompared to the reference sequence of SEQ ID NO:128, 130, or 160. Insome embodiments, the number of differences can be 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40residue differences at other amino acid residues. In some embodiments,the differences comprise conservative mutations. In some embodiments,the ketoreductase polypeptide comprises an amino acid sequence with atleast the preceding features, and wherein the amino acid sequence has atleast 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%,98%, or 99% identity as compared to a reference sequence based on SEQ IDNO:128, 130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X127 is a basic or polar residue, particularlyarginine. In some embodiments, the ketoreductase polypeptides can haveadditionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40residue differences at other amino acid residues as compared to thereference sequence of SEQ ID NO:128, 130, or 160. In some embodiments,the number of differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40 residue differencesat other amino acid residues. In some embodiments, the differencescomprise conservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with at least the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity as compared to a reference sequence based on SEQ ID NO:128,130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X147 is a non-polar, aliphatic, aromatic, orhydrophobic residue, particularly leucine. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X152 is a non-polar, basic residue, orhydrophilic residue, particularly, methionine or lysine. In someembodiments, the ketoreductase polypeptides can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residuedifferences at other amino acid residues as compared to the referencesequence of SEQ ID NO:128, 130, or 160. In some embodiments, the numberof differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with at least the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity as compared to a reference sequence based on SEQ ID NO:128,130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X157 is a polar residue, particularly threonineor serine. In some embodiments, the ketoreductase polypeptides can haveadditionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40residue differences at other amino acid residues as compared to thereference sequence of SEQ ID NO:128, 130, or 160. In some embodiments,the number of differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40 residue differencesat other amino acid residues. In some embodiments, the differencescomprise conservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with at least the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity as compared to a reference sequence based on SEQ ID NO:128,130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X163 is a non-polar or aliphatic residue,particularly isoleucine. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X176 is a non-polar or aliphatic residue,particularly valine. In some embodiments, the ketoreductase polypeptidescan have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35or about 1-40 residue differences at other amino acid residues ascompared to the reference sequence of SEQ ID NO:128, 130, or 160. Insome embodiments, the number of differences can be 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40residue differences at other amino acid residues. In some embodiments,the differences comprise conservative mutations. In some embodiments,the ketoreductase polypeptide comprises an amino acid sequence with atleast the preceding features, and wherein the amino acid sequence has atleast 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%,98%, or 99% identity as compared to a reference sequence based on SEQ IDNO:128, 130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X194 is a basic constrained, basic, or polarresidue, particularly arginine or glutamine. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X197 is a hydrophilic, acidic, basic, aliphaticor a non-polar residue, particularly glutamic acid or valine. In someembodiments, the ketoreductase polypeptides can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residuedifferences at other amino acid residues as compared to the referencesequence of SEQ ID NO:128, 130, or 160. In some embodiments, the numberof differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with at least the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity as compared to a reference sequence based on SEQ ID NO:128,130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X198 is an acidic, basic, hydrophilic, ornon-polar residue, particularly glycine, lysine, or glutamic acid. Insome embodiments, the ketoreductase polypeptides can have additionally1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15,1-16, 1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residuedifferences at other amino acid residues as compared to the referencesequence of SEQ ID NO:128, 130, or 160. In some embodiments, the numberof differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with at least the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity as compared to a reference sequence based on SEQ ID NO:128,130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X199 is an acidic, aliphatic, or non-polarresidue, and particularly aspartic acid. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X200 is an acidic or a constrained residue,particularly proline. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X202 is a non-polar residue, and particularlyglycine. In some embodiments, the ketoreductase polypeptides can haveadditionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40residue differences at other amino acid residues as compared to thereference sequence of SEQ ID NO:128, 130, or 160. In some embodiments,the number of differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40 residue differencesat other amino acid residues. In some embodiments, the differencescomprise conservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with at least the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity as compared to a reference sequence based on SEQ ID NO:128,130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X206 is a non-polar, aromatic, or hydrophobicresidue, and particularly glycine. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-26, 1-30, 1-35 or about 1-40 residue differences at otheramino acid residues as compared to the reference sequence of SEQ IDNO:128, 130, or 160. In some embodiments, the number of differences canbe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24,26, 30, 35 or about 40 residue differences at other amino acid residues.In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, have at leastthe following features: amino acid residue corresponding to X145 is aserine; amino acid residue corresponding to X190 is a cysteine; andamino acid residue corresponding to X211 is a basic residue,particularly arginine. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X223 is a non-polar or aliphatic residue,particularly valine. In some embodiments, the ketoreductase polypeptidescan have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26, 1-30, 1-35or about 1-40 residue differences at other amino acid residues ascompared to the reference sequence of SEQ ID NO:128, 130, or 160. Insome embodiments, the number of differences can be 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40residue differences at other amino acid residues. In some embodiments,the differences comprise conservative mutations. In some embodiments,the ketoreductase polypeptide comprises an amino acid sequence with atleast the preceding features, and wherein the amino acid sequence has atleast 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%,98%, or 99% identity as compared to a reference sequence based on SEQ IDNO:128, 130, or 160 with the preceding features.

In some embodiments, the improved ketoreductase polypeptides comprisingan amino acid sequence based on the sequence formula of SEQ ID NO:161,162 or 163, or region thereof, such as residues 90-211, in which theamino acid sequence has at least the following features: amino acidresidue corresponding to X145 is a polar residue, particularly serine;amino acid residue corresponding to X190 is a cysteine; and amino acidresidue corresponding to X250 is a polar or a non-polar residue,particularly isoleucine. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-26,1-30, 1-35 or about 1-40 residue differences at other amino acidresidues as compared to the reference sequence of SEQ ID NO:128, 130, or160. In some embodiments, the number of differences can be 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 residue differences at other amino acid residues. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to a referencesequence based on SEQ ID NO:128, 130, or 160 with the precedingfeatures.

In some embodiments, an improved ketoreductase comprises an amino acidsequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%,93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acidsequence corresponding to SEQ ID NO: 8, 10, 12, 14, 16, 18, 20, 22, 24,26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60,62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96,or 98 as listed in Tables 3 and 4, wherein the improved ketoreductasepolypeptide amino acid sequence includes any one set of the specifiedamino acid substitution combinations presented in Tables 3 and 4. Insome embodiments, the ketoreductase polypeptides can have additionally1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15,1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40 differencesat other amino acid residues as compared to the reference sequence. Insome embodiments, the number of differences can be 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40residue differences at other amino acid residues. In some embodiments,the differences comprise conservative mutations.

In some embodiments, an improved ketoreductase comprises an amino acidsequence corresponding to SEQ ID NO: 8, 42, 44, 46, 48, 50, 52, 54, 56,58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92,96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124,and 126.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X108 is ahydrophilic, polar or constrained residue, particularly histidine orserine; residue corresponding to X117 is a non-polar or a polar residue,particularly serine; residue corresponding to X145 is a polar residue,particularly serine; residue corresponding to X157 is a polar residue,particularly threonine; residue corresponding to X190 is a cysteine;residue corresponding to X211 is a basic residue, particularly arginine;and residue corresponding to X223 is a non-polar or aliphatic residue,particularly valine. In some embodiments, the ketoreductase polypeptidescan have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35or about 1-40 residue differences at other residue positions as comparedto a reference sequence of SEQ ID NO:8. In some embodiments, the numberof differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 8.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X94 is anon-polar or a polar residue, particularly serine; residue correspondingto X108 is a hydrophilic, polar or constrained residue, particularlyhistidine, residue corresponding to X117 is a non-polar or a polarresidue, particularly serine; residue corresponding to X145 is a polarresidue, particularly serine; residue corresponding to X157 is a polarresidue, particularly threonine; residue corresponding to X190 is acysteine; residue corresponding to X199 is an acidic, aliphatic, ornon-polar residue, particularly aspartic acid; residue corresponding toX211 is a basic residue, particularly arginine; and residuecorresponding to X223 is a non-polar or aliphatic residue, particularlyvaline. In some embodiments, the ketoreductase polypeptides can haveadditionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40residue differences at other residue positions as compared to areference sequence of SEQ ID NO:42. In some embodiments, the number ofdifferences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 42.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X96 is a polarresidue, particularly glutamine; residue corresponding to X108 is ahydrophilic, polar or constrained residue, particularly histidine;residue corresponding to X117 is a non-polar or a polar residue,particularly serine; residue corresponding to X145 is a polar residue,particularly serine; residue corresponding to X157 is a polar residue,particularly threonine; residue corresponding to X190 is cysteine;residue corresponding to X211 is a basic residue, particularly arginine;and residue corresponding to X223 is a non-polar or aliphatic residue,particularly valine. In some embodiments, the ketoreductase polypeptidescan have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35or about 1-40 residue differences at other residue positions as comparedto a reference sequence of SEQ ID NO:44. In some embodiments, the numberof differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 44.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X108 is ahydrophilic, polar or constrained residue, particularly histidine;residue corresponding to X117 is non-polar or a polar residue,particularly serine; residue corresponding to X145 is a polar residue,particularly serine; residue corresponding to X157 is a polar residue,particularly threonine; residue corresponding to X190 is a cysteine;residue corresponding to X199 is an acidic, aliphatic, or non-polarresidue, particularly aspartic acid; residue corresponding to X211 is abasic residue, particularly arginine; and residue corresponding to X223is a non-polar or aliphatic residue, particularly valine. In someembodiments, the ketoreductase polypeptides can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40 residuedifferences at other residue positions as compared to a referencesequence of SEQ ID NO:46. In some embodiments, the number of differencescan be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22,24, 26, 30, 35 or about 40 residue differences at other amino acidresidues. In some embodiments, the differences comprise conservativemutations. In some embodiments, the ketoreductase polypeptide comprisesan amino acid sequence with the preceding features, and wherein theamino acid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%,93%, 94%, 95%, 96%, 97%, 98%, or 99% identity to SEQ ID NO: 46.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X108 ishydrophilic, polar or constrained residue, particularly histidine;residue corresponding to X117 is non-polar or a polar residue,particularly serine; residue corresponding to X145 is a polar residue,particularly serine; residue corresponding to X157 is a polar residue,particularly threonine; residue corresponding to X190 is cysteine;residue corresponding to X202 is a is a non-polar residue or aliphaticresidue, particularly glycine; residue corresponding to X211 is a basicresidue, particularly arginine; and residue corresponding to X223 is anon-polar or aliphatic residue, particularly valine. In someembodiments, the ketoreductase polypeptides can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40 residuedifferences at other residue positions as compared to a referencesequence of SEQ ID NO:48. In some embodiments, the number of differencescan be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22,24, 26, 30, 35 or about 40 residue differences at other amino acidresidues. In some embodiments, the differences comprise conservativemutations. In some embodiments, the ketoreductase polypeptide comprisesan amino acid sequence with the preceding features, and wherein theamino acid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%,93%, 94%, 95%, 96%, 97%, 98%, or 99% identity to SEQ ID NO: 48.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X108 is ahydrophilic, polar or constrained residue, particularly histidine;residue corresponding to X117 is a non-polar or a polar residue,particularly serine; residue corresponding to X145 is a polar residue,particularly serine; residue corresponding to X152 is a non-polar orbasic residue, particularly methionine or lysine; residue correspondingto X157 is a polar residue, particularly threonine; residuecorresponding to X190 is a cysteine; residue corresponding to X199 is anacidic, aliphatic, or non-polar residue, particularly aspartic acid;residue corresponding to X211 is a basic residue, particularly arginine;and residue corresponding to X223 is a non-polar or aliphatic residue,particularly valine. In some embodiments, the ketoreductase polypeptidescan have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35or about 1-40 residue differences at other residue positions as comparedto a reference sequence of SEQ ID NO:52 or 54. In some embodiments, thenumber of differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14,15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40 residue differences atother amino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to 52 or 54.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X94 is anon-polar or a polar residue, particularly serine; residue correspondingto X96 is a polar residue, particularly glutamine; residue correspondingto X108 is a hydrophilic, polar or constrained residue, particularlyhistidine; residue corresponding to X117 is a non-polar or a polarresidue, particularly serine; residue corresponding to X145 is a polarresidue, particularly serine; residue corresponding to X157 is a polarresidue, particularly threonine; residue corresponding to X190 is acysteine; residue corresponding to X199 is an acidic, aliphatic, ornon-polar residue, particularly aspartic acid; residue corresponding toX211 is a basic residue, particularly arginine; and residuecorresponding to X223 is a non-polar or aliphatic residue, particularlyvaline. In some embodiments, the ketoreductase polypeptides can haveadditionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40residue differences at other residue positions as compared to areference sequence of SEQ ID NO:56. In some embodiments, the number ofdifferences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO:56.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: corresponding to X7 is a non-polar or polar residue,particularly serine; residue corresponding to X108 is a hydrophilic,polar or constrained residue, particularly histidine; residuecorresponding to X117 is a non-polar or a polar residue, particularlyserine; residue corresponding to X145 is a polar residue, particularlyserine; residue corresponding to X157 is a polar residue, particularlythreonine; residue corresponding to X190 is a cysteine; residuecorresponding to X194 is a constrained, basic, or polar residue,particularly arginine; residue corresponding to X199 is an acidic,aliphatic, or non-polar residue, particularly aspartic acid; and residuecorresponding to X211 is a basic residue. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40 residue differences at otherresidue positions as compared to a reference sequence of SEQ ID NO:58.In some embodiments, the number of differences can be 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40residue differences at other amino acid residues. In some embodiments,the differences comprise conservative mutations. In some embodiments,the ketoreductase polypeptide comprises an amino acid sequence with thepreceding features, and wherein the amino acid sequence has at least85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or99% identity to SEQ ID NO: 58.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X96 is a polarresidue, particularly glutamine or threonine; residue corresponding toX108 is a hydrophilic, polar or constrained residue, particularly,histidine; residue corresponding to X117 is a non-polar or a polarresidue, particularly serine; residue corresponding to X145 is a polarresidue, particularly serine; residue corresponding to X152 is anon-polar, basic residue, or hydrophilic residue, particularlymethionine; residue corresponding to X157 is a polar residue,particularly threonine; residue corresponding to X190 is a cysteine;residue corresponding to X194 is a constrained, basic, or polar residue,particularly arginine; residue corresponding to X199 is an acidic,aliphatic, or non-polar residue, particularly aspartic acid; residuecorresponding to X211 is a basic residue, particularly arginine; andresidue corresponding to X223 is a non-polar or aliphatic residue,particularly valine. In some embodiments, the ketoreductase polypeptidescan have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35or about 1-40 residue differences at other residue positions as comparedto a reference sequence of SEQ ID NO:72 or 74. In some embodiments, thenumber of differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14,15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40 residue differences atother amino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 72 or 74.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X25 is an acidic,non-polar or polar residue, particularly threonine; residuecorresponding to X40 is a constrained, basic, or hydrophilic residue;residue corresponding to X75 is an acidic or polar residue, particularlyasparagine; residue corresponding to X96 is a polar residue,particularly glutamine; residue corresponding to X108 is a hydrophilic,polar or constrained residue, particularly histidine; residuecorresponding to X117 is a non-polar or a polar residue, particularlyserine; residue corresponding to X145 is a polar residue, particularlyserine; residue corresponding to X152 is a non-polar, basic residue, orhydrophilic residue, particularly methionine; residue corresponding toX157 is a polar residue, particularly threonine; residue correspondingto X190 is a cysteine; residue corresponding to X199 is an acidic,aliphatic, or non-polar residue, particularly aspartic acid; residuecorresponding to X211 is a basic residue, particularly arginine, andresidue X223 is a non-polar or aliphatic residue, particularly valine.In some embodiments, the ketoreductase polypeptides can haveadditionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40residue differences at other residue positions as compared to areference sequence of SEQ ID NO:76. In some embodiments, the number ofdifferences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: SEQ ID NO: 76.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X25 is a acidic,non-polar or polar residue, particularly threonine; residuecorresponding to X95 is a non-polar or aliphatic residue, particularlyleucine; residue corresponding to X96 is a polar residue, particularlyglutamine; residue corresponding to X108 is a hydrophilic, polar orconstrained residue, particularly histidine; residue corresponding toX117 is a non-polar or a polar residue, particularly serine; residuecorresponding to X145 is a polar residue, particularly serine; residuecorresponding to X152 is a non-polar, basic residue, or hydrophilicresidue, particularly methionine; residue corresponding to X176 isnon-polar or aliphatic residue, particularly valine; residuecorresponding to X190 is a cysteine; residue corresponding to X198 is anacidic, basic, hydrophilic, or non-polar residue, particularly glutamicacid; residue corresponding to X199 is an acidic, aliphatic, ornon-polar residue, particularly aspartic acid; residue corresponding toX211 is a basic residue, particularly arginine; and residuecorresponding to X223 is a non-polar or aliphatic residue, particularlyvaline. In some embodiments, the ketoreductase polypeptides can haveadditionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40residue differences at other residue positions as compared to areference sequence of SEQ ID NO:82. In some embodiments, the number ofdifferences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 82.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X25 is an acidic,non-polar or polar residue, particularly threonine; residuecorresponding to X95 is a non-polar or aliphatic residue, particularlyleucine; residue corresponding to X96 is a polar residue, particularlyglutamine; residue corresponding to X108 is a hydrophilic, polar orconstrained residue, particularly histidine; residue corresponding toX117 is a non-polar or a polar residue, particularly serine; residuecorresponding to X145 is a polar residue, particularly serine; residuecorresponding to X152 is a non-polar, basic residue, or hydrophilicresidue, particularly methionine; residue corresponding to X176 is anon-polar or aliphatic residue, particularly valine; residuecorresponding to X190 is a cysteine; residue corresponding to X197 is ahydrophilic, acidic, basic, aliphatic or a non-polar residue,particularly valine; residue corresponding to X199 is an acidic,aliphatic, or non-polar residue, particularly aspartic acid; residuecorresponding to X211 is a basic residue, particularly arginine; andresidue corresponding to X223 is a non-polar or aliphatic residue,particularly valine. In some embodiments, the ketoreductase polypeptidescan have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35or about 1-40 residue differences at other residue positions as comparedto a reference sequence of SEQ ID NO:84. In some embodiments, the numberof differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 84.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X25 is a acidic,non-polar or polar residue, particularly threonine; residuecorresponding to X95 is a non-polar or aliphatic residue, particularlymethionine; residue corresponding to X96 is a polar residue,particularly glutamine; residue corresponding to X108 is a hydrophilic,polar or constrained residue, particularly histidine; residuecorresponding to X117 is a non-polar or a polar residue, particularlyserine; residue corresponding to X145 is a polar residue, particularlyserine; residue corresponding to X152 is a non-polar, basic residue, orhydrophilic residue, particularly methionine; residue corresponding toX176 is a non-polar or aliphatic residue, particularly valine; residuecorresponding to X190 is a cysteine; residue corresponding to X194 is aconstrained, basic, or polar residue, particularly arginine; residuecorresponding to X199 is an acidic, aliphatic, or non-polar residue,particularly aspartic acid; residue corresponding to X211 is a basicresidue, particularly arginine; and residue corresponding to X223 is anon-polar or aliphatic residue, particularly valine. In someembodiments, the ketoreductase polypeptides can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40 residuedifferences at other residue positions as compared to a referencesequence of SEQ ID NO:86. In some embodiments, the number of differencescan be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22,24, 26, 30, 35 or about 40 residue differences at other amino acidresidues. In some embodiments, the differences comprise conservativemutations. In some embodiments, the ketoreductase polypeptide comprisesan amino acid sequence with the preceding features, and wherein theamino acid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%,93%, 94%, 95%, 96%, 97%, 98%, or 99% identity to SEQ ID NO: SEQ ID NO:86.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X96 is a polarresidue, particularly glutamine; residue corresponding to X145 is apolar residue, particularly serine; residue corresponding to X152 is anon-polar, basic residue, or hydrophilic residue, particularlymethionine; residue corresponding to X190 is a cysteine; residuecorresponding to X199 is an acidic, aliphatic, or non-polar residue,particularly aspartic acid; and residue corresponding to X211 is a basicresidue, particularly arginine. In some embodiments, the ketoreductasepolypeptides can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25,1-30, 1-35 or about 1-40 residue differences at other residue positionsas compared to a reference sequence of SEQ ID NO:90. In someembodiments, the number of differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40 residuedifferences at other amino acid residues. In some embodiments, thedifferences comprise conservative mutations. In some embodiments, theketoreductase polypeptide comprises an amino acid sequence with thepreceding features, and wherein the amino acid sequence has at least85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or99% identity to SEQ ID NO: 90.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X53 is anon-polar or an acidic residue, particularly aspartic acid; residuecorresponding to X96 is a polar residue, particularly glutamine; residuecorresponding to X108 is a hydrophilic, polar or constrained residue,particularly histidine; residue corresponding to X117 is a non-polar ora polar residue, particularly serine; residue corresponding to residueX145 is a polar residue, particularly serine; residue corresponding toX152 is a non-polar, basic residue, or hydrophilic residue, particularlymethionine; residue corresponding to X163 is a non-polar or aliphaticresidue, particularly isoleucine; residue corresponding to X190 is acysteine; residue corresponding to X199 is an acidic, aliphatic, ornon-polar residue, particularly aspartic acid; residue corresponding toX211 is a basic residue, particularly arginine; and residuecorresponding to X223 is a non-polar or aliphatic residue, particularlyvaline. In some embodiments, the ketoreductase polypeptides can haveadditionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40residue differences at other residue positions as compared to areference sequence of SEQ ID NO:94. In some embodiments, the number ofdifferences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 94.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X96 is a polarresidue, particularly glutamine; residue corresponding to X101 isacidic, non-polar, or a polar residue, particularly glycine; residuecorresponding to X108 is hydrophilic, polar or constrained residue,particularly histidine; residue corresponding to X117 is non-polar or apolar residue, particularly serine; residue corresponding to X145 is apolar residue, particularly serine; residue corresponding to X147 isnon-polar, aliphatic, aromatic, or hydrophobic residue, particularlyleucine; residue corresponding to X152 is non-polar, basic residue,particularly methionine; residue corresponding to X190 is cysteine;residue corresponding to X199 is an acidic, aliphatic, or non-polarresidue, particularly aspartic acid; residue corresponding to X211 is abasic residue, particularly arginine; and residue corresponding to X223is a non-polar or aliphatic residue, particularly valine. In someembodiments, the ketoreductase polypeptides can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40 residuedifferences at other residue positions as compared to a referencesequence of SEQ ID NO:100. In some embodiments, the number ofdifferences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 100.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X96 is a polarresidue, particularly glutamine; residue corresponding to X108 is ahydrophilic, polar or constrained residue, particularly histidine;residue corresponding to X111 is a non-polar or aliphatic residue,particularly methionine; residue corresponding to X117 is a non-polar ora polar residue, particularly serine; residue corresponding to X145 is apolar residue, particularly serine; residue corresponding to X152 is anon-polar, basic residue, or hydrophilic residue, particularlymethionine; residue corresponding to X190 is a cysteine; residuecorresponding to X199 is an acidic, aliphatic, or non-polar residue,particularly aspartic acid; residue corresponding to X211 is a basicresidue, particularly arginine; and residue corresponding to X223 is anon-polar or aliphatic residue, particularly valine. In someembodiments, the ketoreductase polypeptides can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40 residuedifferences at other residue positions as compared to a referencesequence of SEQ ID NO:102. In some embodiments, the number ofdifferences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 102.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X96 is a polarresidue, particularly glutamine; residue corresponding to X108 is ahydrophilic, polar or constrained residue, particularly histidine;residue corresponding to X117 is a non-polar or a polar residue,particularly serine; residue corresponding to X145 is a polar residue,particularly serine; residue corresponding to X152 is a non-polar, basicresidue, or hydrophilic residue, particularly methionine; residuecorresponding to X190 is a cysteine; residue corresponding to X199 is anacidic, aliphatic, or non-polar residue, particularly aspartic acid;residue corresponding to X211 is a basic residue, particularly arginine;and residue corresponding to X223 is a non-polar or aliphatic residue,particularly valine; and residue corresponding to X250 is a polar ornon-polar residue, particularly isoleucine. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40 residue differences at otherresidue positions as compared to a reference sequence of SEQ ID NO:104.In some embodiments, the number of differences can be 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40residue differences at other amino acid residues. In some embodiments,the differences comprise conservative mutations. In some embodiments,the ketoreductase polypeptide comprises an amino acid sequence with thepreceding features, and wherein the amino acid sequence has at least85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or99% identity to SEQ ID NO:104.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X29 is an acidic,aliphatic or non-polar residue, particularly glycine; residuecorresponding to X96 is a polar residue, particularly glutamine; residuecorresponding to X101 is an acidic, non-polar, or a polar residue,particularly asparagine; residue corresponding to X108 is a hydrophilic,polar or constrained residue, particularly histidine; residuecorresponding to X117 is a non-polar or polar residue, particularlyserine; residue corresponding to X145 is a polar residue, particularlyserine; residue corresponding to X152 is a non-polar, basic residue, orhydrophilic residue, particularly methionine; residue corresponding toX190 is a cysteine; residue corresponding to X199 is an acidic,aliphatic, or non-polar residue, particularly aspartic acid; residuecorresponding to X200 is an acidic or a constrained residue,particularly proline; residue corresponding to X211 is a basic residue,particularly arginine, and residue corresponding to X223 is a non-polaror aliphatic residue, particularly valine. In some embodiments, theketoreductase polypeptides can have additionally 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20,1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40 residue differences at otherresidue positions as compared to a reference sequence of SEQ ID NO:106.In some embodiments, the number of differences can be 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40residue differences at other amino acid residues. In some embodiments,the differences comprise conservative mutations. In some embodiments,the ketoreductase polypeptide comprises an amino acid sequence with thepreceding features, and wherein the amino acid sequence has at least85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or99% identity to SEQ ID NO: 106.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X3 is an acidic, polar, orhydrophilic residue, particularly asparagine; residue corresponding toX7 is a non-polar or polar residue, particularly serine; residuecorresponding to X17 is a non-polar, aliphatic or polar residue,particularly glutamine; residue corresponding to X42 is an acidic ornon-polar residue, particularly glycine; residue corresponding to X96 isa polar residue, particularly glutamine; residue corresponding to X108is a hydrophilic, polar or constrained residue, particularly histidine;residue corresponding to X127 is a basic or polar residue, particularlyarginine; residue corresponding to X145 is a polar residue, particularlyserine; residue corresponding to X152 is a non-polar, basic residue, orhydrophilic residue, particularly methionine; residue corresponding toX176 is a non-polar or aliphatic residue, particularly valine; residuecorresponding to X190 is a cysteine; residue corresponding to X194 is aconstrained, basic, or polar residue, particularly arginine; residuecorresponding to X199 is an acidic, aliphatic, or non-polar residue,particularly aspartic acid; residue corresponding to X200 is an acidicor a constrained residue, particularly proline; residue corresponding toX211 is a basic residue, particularly arginine; and residuecorresponding to X223 is a non-polar or aliphatic residue, particularlyvaline. In some embodiments, the ketoreductase polypeptides can haveadditionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40residue differences at other residue positions as compared to areference sequence of SEQ ID NO:114. In some embodiments, the number ofdifferences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 114.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X3 is an acidic, polar, orhydrophilic residue, particularly asparagine; residue corresponding toX7 is a non-polar or polar residue, particularly serine; residuecorresponding to X17 is a non-polar, aliphatic or polar residue,particularly glutamine; residue corresponding to X21 is a non-polar,aromatic, or hydrophobic residue, particularly phenylalanine; residuecorresponding to X96 is a polar residue, particularly glutamine; residuecorresponding to X108 is a hydrophilic, polar or constrained residue,particularly histidine; residue corresponding to X145 is a polarresidue, particularly serine; residue corresponding to X147 is anon-polar, aliphatic, aromatic, or hydrophobic residue, particularlyleucine; residue corresponding to X152 is a non-polar, basic, orhydrophilic residue, particularly methionine; residue corresponding toX176 is a non-polar or aliphatic residue, particularly valine; residuecorresponding to X190 is a cysteine; residue corresponding to X199 is anacidic, aliphatic, or non-polar residue, particularly aspartic acid;residue corresponding to X211 is a basic residue, particularly arginine;and residue corresponding to X223 is a non-polar or aliphatic residue,particularly valine. In some embodiments, the ketoreductase polypeptidescan have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35or about 1-40 residue differences at other residue positions as comparedto a reference sequence of SEQ ID NO:116. In some embodiments, thenumber of differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14,15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40 residue differences atother amino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO:116.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X3 is an acidic, polar, orhydrophilic residue, particularly asparagine; residue corresponding toX7 is a non-polar or polar residue, particularly serine; residuecorresponding to X17 is a non-polar, aliphatic or polar residue,particularly glutamine; residue corresponding to X29 is an acidic,aliphatic or non-polar residue, particularly alanine; residuecorresponding to X42 is an acidic or non-polar residue, particularlyglycine; residue corresponding to X96 is a polar residue, particularlyglutamine; residue corresponding to X105 is an acidic or non-polarresidue, particularly glycine; residue corresponding to X108 is ahydrophilic, polar or constrained residue, particularly histidine;residue corresponding to X117 is a non-polar or a polar residue,particularly serine; residue corresponding to X145 is a polar residue,particularly serine; residue corresponding to X152 is a non-polar,basic, or hydrophilic residue, particularly methionine; residuecorresponding to X190 is a cysteine; residue corresponding to X197 is ahydrophilic, acidic, basic, aliphatic or a non-polar residue,particularly valine; residue corresponding to X198 is an acidic, basic,hydrophilic, or non-polar residue, particularly lysine; residuecorresponding to X199 is an acidic, aliphatic, or non-polar residue,particularly aspartic acid; residue corresponding to X200 is an acidicor a constrained residue, particularly proline; residue corresponding toX211 is a basic residue, particularly arginine; and residuecorresponding to X223 is a non-polar or aliphatic residue, particularlyvaline. In some embodiments, the ketoreductase polypeptides can haveadditionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40residue differences at other residue positions as compared to areference sequence of SEQ ID NO:118. In some embodiments, the number ofdifferences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 118.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X17 is anon-polar, aliphatic or polar residue, particularly glutamine; residueX29 is an acidic, aliphatic or non-polar residue, particularly alanine;residue corresponding to X96 is a polar residue, particularly glutamine;residue corresponding to X108 is a hydrophilic, polar or constrainedresidue, particularly histidine; residue corresponding to X117 is anon-polar or a polar residue, particularly serine; residue correspondingto X145 is a polar residue, particularly serine; residue correspondingto X152 is a non-polar, basic, or hydrophilic residue, particularlymethionine; residue corresponding to X163 is a non-polar or aliphaticresidue, particularly isoleucine; residue corresponding to X190 is acysteine; residue corresponding to X198 is an acidic, basic,hydrophilic, or non-polar residue, particularly lysine; residuecorresponding to X199 is an acidic, aliphatic, or non-polar residue,particularly aspartic acid; residue corresponding to X200 is an acidicor a constrained residue, particularly proline; and residuecorresponding to X211 is a basic residue, particularly arginine. In someembodiments, the ketoreductase polypeptides can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40 residuedifferences at other residue positions as compared to a referencesequence of SEQ ID NO:122. In some embodiments, the number ofdifferences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16,18, 20, 22, 24, 26, 30, 35 or about 40 residue differences at otheramino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO:122.

In some embodiments, an improved ketoreductase comprises an amino acidsequence based on the sequence formula of SEQ ID NO:161, 162 or 163, ora region thereof, such as residues 90 to 211, and has at least thefollowing features: residue corresponding to X7 is a non-polar or polarresidue, particularly serine; residue corresponding to X17 is anon-polar, aliphatic or polar residue, particularly glutamine; residuecorresponding to X29 is an acidic, aliphatic or non-polar residue,particularly alanine; residue corresponding to X96 is a polar residue,particularly glutamine; residue corresponding to X108 is a hydrophilic,polar or constrained residue, particularly histidine; residuecorresponding to X117 is a non-polar or a polar residue, particularlyserine; residue corresponding to X145 is polar residue, particularlyserine; residue corresponding to X147 is a non-polar, aliphatic,aromatic, or hydrophobic residue, particularly leucine; residuecorresponding to X152 is a non-polar, basic, or hydrophilic residue,particularly methionine; residue corresponding to X163 is a non-polar oraliphatic residue, particularly isoleucine; residue corresponding toX176 is a non-polar or aliphatic residue, particularly valine; residuecorresponding to X190 is a cysteine; residue corresponding to X198 is anacidic, basic, hydrophilic, or non-polar residue, particularly lysine;residue corresponding to X199 is an acidic, aliphatic, or non-polarresidue, particularly aspartic acid; residue corresponding to X200 is anacidic or a constrained residue, particularly proline; residuecorresponding to X211 is a basic residue, particularly arginine; andresidue corresponding to X223 is a non-polar or aliphatic residue,particularly valine. In some embodiments, the ketoreductase polypeptidescan have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10,1-11, 1-12, 1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35or about 1-40 residue differences at other residue positions as comparedto a reference sequence of SEQ ID NO:126. In some embodiments, thenumber of differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14,15, 16, 18, 20, 22, 24, 26, 30, 35 or about 40 residue differences atother amino acid residues. In some embodiments, the differences compriseconservative mutations. In some embodiments, the ketoreductasepolypeptide comprises an amino acid sequence with the precedingfeatures, and wherein the amino acid sequence has at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identity to SEQ ID NO: 126.

In some embodiments, an improved ketoreductase comprises an amino acidsequence that has a region or domain corresponding to residues 90-211 ofthe sequence formula of SEQ ID NO:161, 162 or 163, in which the aminoacid sequence of the domain has at least the following features: theamino acid residue corresponding to X145 is a polar residue, and theamino acid residue corresponding to X190 is a cysteine. In someembodiments, the improved ketoreductase has a region or domain thatcorresponds to residues 90-211 based on the sequence formula of SEQ IDNO:161, 162 or 163, in which the amino acid sequence of the domain hasat least the following features: the amino acid residue corresponding toX145 is a serine, and the amino acid residue corresponding to X190 is acysteine. In some embodiments, the region or domain corresponding toresidues 90-211 can have additionally 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8,1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, or 1-20 residuedifferences at other amino acid residues as compared to thecorresponding domain of a reference sequence based on SEQ ID NO:128,130, or 160. In some embodiments, the number of differences can be 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, or about 20 residuedifferences at other amino acid residues in the domain. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to the amino acidsequence corresponding to residues 90-211 of a reference sequence basedon SEQ ID NO:128, 130, Or 160 with the preceding features.

In some embodiments, the ketoreductase polypeptides with a domain orregion corresponding to residues 90-211 and having the specifiedfeatures for residues X145 and X190 as described herein, can furtherinclude in the region or domain one or more features selected from thefollowing: residue corresponding to X94 is a non-polar or a polarresidue; residue corresponding to X95 is a non-polar or aliphaticresidue; residue corresponding to X96 is a polar residue; residuecorresponding to X101 is an acidic, non-polar, or a polar residue;residue corresponding to X105 is an acidic or non-polar residue; residuecorresponding to X108 is a hydrophilic, polar or constrained residue;residue corresponding to X111 is a non-polar or aliphatic residue;residue corresponding to X112 is an acidic or polar residue; residuecorresponding to X113 is a non-polar or aliphatic residue; residuecorresponding to X117 is a non-polar or a polar residue; residuecorresponding to X127 is a basic or polar residue; residue correspondingto X147 is a non-polar, aliphatic, aromatic, or hydrophobic residue;residue corresponding to X152 is a non-polar, basic, or hydrophilicresidue; residue corresponding to X157 is a polar residue; residuecorresponding to X163 is a non-polar or aliphatic residue; residuecorresponding to X176 is a non-polar or aliphatic residue; residuecorresponding to X194 is a constrained, basic, or polar residue; residuecorresponding to X197 is a hydrophilic, acidic, basic, aliphatic or anon-polar residue; residue corresponding to X198 is an acidic, basic,hydrophilic, or non-polar residue; residue corresponding to X199 is anacidic, aliphatic, or non-polar residue; residue corresponding to X200is an acidic or constrained residue; residue corresponding to X202 is anon-polar residue; residue corresponding to X206 is a non-polar,aromatic, or hydrophobic residue; residue corresponding to X211 is abasic residue. In some embodiments, the region or domain correspondingto residues 90-211 can have additionally from about 1-2, 1-3, 1-4, 1-5,1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, or 1-20residue differences at other amino acid residues as compared to thecorresponding domain of a reference sequence based on SEQ ID NO:128,130, or 160. In some embodiments, the number of differences can be 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, or about 20 residuedifferences at other amino acid residues in the domain. In someembodiments, the differences comprise conservative mutations.

In some embodiments, the ketoreductases polypeptides having a domainwith an amino acid sequence corresponding to residues 90-211 of thesequence formula of SEQ ID NO:161, 162 or 163, as described above, canhave one or more conservative mutations as compared to the correspondingdomain of SEQ ID NO:128, 130, or 160. Examples of such conservativemutations include amino acid replacements such as, but not limited to:the replacement of residue corresponding to X95 (valine) with anothernon-polar amino acid, e.g., alanine, leucine, isoleucine, glycine, ormethionine; the replacement of residue corresponding to X96 (serine)with another polar amino acid, e.g., asparagine, glutamine, orthreonine; the replacement of residue corresponding to X111 (leucine)with another non-polar amino acid, e.g., alanine, leucine, isoleucine,glycine, or methionine; the replacement of residue corresponding to X113(valine) with another aliphatic amino acid, e.g., alanine, leucine, orisoleucine; the replacement of residue corresponding to X157(asparagine) with another polar amino acid, e.g., glutamine, serine, orthreonine; the replacement of residue corresponding to X163 (valine)with another aliphatic amino acid, e.g., alanine, leucine, orisoleucine; the replacement of residue corresponding to X176 (leucine)with another aliphatic amino acid, e.g., alanine, valine, andisoleucine; the replacement of residue corresponding to X202 (alanine)with another non-polar amino acid, e.g., alanine, leucine, isoleucine,glycine, or methionine; and the replacement of residue corresponding toX211 (lysine) with another basic amino acid, e.g., arginine.

In some embodiments, the ketoreductase polypeptides with a domain orregion corresponding to residues 90-211 and having the specifiedfeatures for residues X145 and X190 as described herein, can furtherinclude in the region or domain one or more features selected from thefollowing: residue corresponding to X94 is glycine, methionine, alanine,valine, leucine, isoleucine, serine, threonine, asparagine, orglutamine, particularly asparagine, glycine, or serine; residuecorresponding to X95 is a glycine, methionine, alanine, valine, leucine,or isoleucine, particularly leucine or methionine; residue correspondingto X96 is serine, threonine, asparagine, glutamine, particularlyglutamine, asparagine, or threonine; residue; residue corresponding toX101 is aspartic acid, glutamic acid, serine, threonine, asparagine,glutamine, or glycine, methionine, alanine, valine, leucine, orisoleucine, particularly glycine or asparagine; residue corresponding toX105 is glutamic acid, aspartic acid, glycine, methionine, alanine,valine, leucine, isoleucine, particularly glycine; residue correspondingto X108 is arginine, lysine, serine, threonine, asparagine, glutamine,histidine, particularly histidine or serine; residue corresponding toX112 aspartic acid, glutamic acid, serine, threonine, asparagine,glutamine, particularly aspartic acid; residue corresponding to X113 isan glycine, methionine, alanine, valine, leucine, isoleucine,particularly alanine; residue corresponding to X117 is glycine,methionine, alanine, valine, leucine, isoleucine, serine, threonine,asparagine, or glutamine, particularly serine; residue corresponding toX127 is lysine, arginine, serine, threonine, asparagine, or glutamine,particularly arginine; residue corresponding to X147 is glycine,methionine, alanine, valine, leucine, isoleucine, tyrosine,phenylalanine, tryptophan, particularly leucine; residue correspondingto X152 is glycine, methionine, valine, leucine, isoleucine, arginine,lysine, serine threonine, asparagine, or glutamine, particularlymethionine or lysine; residue corresponding to X157 is a serine,threonine, asparagine, and glutamine, particularly threonine; residuecorresponding to X163 is a glycine, methionine, alanine, valine,leucine, or isoleucine, particularly isoleucine; residue correspondingto X176 is glycine, methionine, alanine, valine, leucine, or isoleucine,particularly valine; residue corresponding to X194 is proline, arginine,lysine, serine, threonine, asparagine, glutamine, particularly arginineor glutamine; residue corresponding to X197 is aspartic acid, glutamicacid, arginine, lysine, serine, threonine, asparagine, glutamine,glycine, methionine, alanine, valine, leucine, isoleucine, particularlyvaline or glutamic acid; residue corresponding to X198 is aspartic acid,glutamic acid, arginine, lysine, serine, threonine, asparagine,glutamine, glycine, methionine, alanine, valine, leucine, or isoleucine,particularly glycine, glutamic acid, or lysine; residue corresponding toX199 is an aspartic acid, glutamic acid, glycine, methionine, alanine,valine, leucine, or isoleucine, particularly aspartic acid; residuecorresponding to X200 is aspartic acid, glutamic acid, or proline,particularly proline; residue corresponding to X202 is glycine,methionine, alanine, valine, leucine, isoleucine, particularly glycine;residue corresponding to X206 is a glycine, methionine, alanine, valine,leucine, isoleucine, tyrosine, phenylalanine, tryptophan, particularlyglycine; residue corresponding to X211 is a arginine or lysine. In someembodiments, the region or domain corresponding to residues 90-211 canhave additionally from about 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9,1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, or 1-20 residue differences atother amino acid residues as compared to the corresponding domain of areference sequence based on SEQ ID NO:128, 130, or 160. In someembodiments, the number of differences can be 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 14, 15, 16, 18, or about 20 residue differences at otheramino acid residues in the domain. In some embodiments, the differencescomprise conservative mutations.

In some embodiments, the ketoreductase polypeptides with a domain orregion corresponding to residues 90-211 and having the specifiedfeatures for residues X145 and X190 as described herein, can furtherinclude in the region or domain one or more features selected from thefollowing: residue corresponding to X108 is a hydrophilic, polar orconstrained residue; residue corresponding to X117 is a non-polar or apolar residue; residue corresponding to X152 is a non-polar, basic, orhydrophilic residue; and residue corresponding to X199 is an acidic,aliphatic, or non-polar residue. In some embodiments, the region ordomain corresponding to residues 90-211 can have additionally 1-2, 1-3,1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18,or 1-20 residue differences at other amino acid residues as compared tothe domain of a reference sequence based on SEQ ID NO:128, 130, or 160.In some embodiments, the number of differences can be 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 14, 15, 16, 18, or about 20 residue differences atother amino acid residues in the domain.

In some embodiments, the differences comprise conservative mutations. Insome embodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to the amino acidsequence corresponding to residues 90-211 of a reference sequence basedon SEQ ID NO:128, 130, or 160 with the preceding features.

In some embodiments, the ketoreductase polypeptides with a domain orregion corresponding to residues 90-211 and having the specifiedfeatures for residues X145 and X190 as described herein, can furtherinclude in the region or domain one or more features selected from thefollowing: residue corresponding to X108 is arginine, lysine, serine,threonine, asparagine, glutamine, histidine, particularly histidine orserine; residue corresponding to X117 is glycine, methionine, alanine,valine, leucine, isoleucine, serine, threonine, asparagine, orglutamine, particularly serine; residue corresponding to X152 isglycine, methionine, valine, leucine, isoleucine, arginine, lysine,serine threonine, asparagine, or glutamine, particularly methionine orlysine; and residue corresponding to X199 is an aspartic acid, glutamicacid, glycine, methionine, alanine, valine, leucine, or isoleucine,particularly aspartic acid. In some embodiments, the region or domaincorresponding to residues 90-211 can have additionally 1-2, 1-3, 1-4,1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, or1-20 residue differences at other amino acid residues as compared to thedomain of a reference sequence based on SEQ ID NO:128, 130, or 160. Insome embodiments, the number of differences can be 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 14, 15, 16, 18, or about 20 residue differences atother amino acid residues in the domain. In some embodiments, thedifferences comprise conservative mutations. In some embodiments, theketoreductase polypeptide comprises an amino acid sequence with at leastthe preceding features, and wherein the amino acid sequence has at least85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or99% identity as compared to the amino acid sequence corresponding toresidues 90-211 of a reference sequence based on SEQ ID NO:128, 130, or160 with the preceding features.

In some embodiments, the ketoreductase polypeptides with a domain orregion corresponding to residues 90-211 and having the specifiedfeatures for residues X145 and X190 as described herein, can furtherinclude in the region or domain one or more features selected from thefollowing: residue corresponding to X94 is a non-polar or a polarresidue; residue corresponding to X194 is a constrained, basic, or polarresidue; residue corresponding to X198 is an acidic, basic, hydrophilic,or non-polar residue; and residue corresponding to X200 is an acidic ora constrained residue. In some embodiments, the region or domaincorresponding to residues 90-211 can have additionally 1-2, 1-3, 1-4,1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18, or1-20 residue differences at other amino acid residues as compared to thedomain of a reference sequence based on SEQ ID NO:128, 130, or 160. Insome embodiments, the number of differences can be 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 14, 15, 16, 18, or about 20 residue differences atother amino acid residues in the domain. In some embodiments, thedifferences comprise conservative mutations. In some embodiments, theketoreductase polypeptide comprises an amino acid sequence with at leastthe preceding features, and wherein the amino acid sequence has at least85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or99% identity as compared to the amino acid sequence corresponding toresidues 90-211 of a reference sequence based on SEQ ID NO:128, 130, or160 with the preceding features. In some embodiments, the region ordomain corresponding to residues 90-211 can have additionally 1-2, 1-3,1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16, 1-18,or 1-20 residue differences at other amino acid residues as compared tothe domain of a reference sequence based on SEQ ID NO:128, 130, or 160.In some embodiments, the number of differences can be 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 14, 15, 16, 18, or about 20 residue differences atother amino acid residues in the domain. In some embodiments, thedifferences comprise conservative mutations. In some embodiments, theketoreductase polypeptide comprises an amino acid sequence with at leastthe preceding features, and wherein the amino acid sequence has at least85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or99% identity as compared to the amino acid sequence corresponding toresidues 90-211 of a reference sequence based on SEQ ID NO:128, 130, or160 with the preceding features.

In some embodiments, the ketoreductase polypeptides with a domain orregion corresponding to residues 90-211 and having the specifiedfeatures for residues X145 and X190 as described herein, can furtherinclude in the region or domain one or more features selected from thefollowing: residue corresponding to X94 is glycine, methionine, alanine,valine, leucine, isoleucine, serine, threonine, asparagine, orglutamine, particularly asparagine, glycine, or serine; residuecorresponding to X194 is proline, arginine, lysine, serine, threonine,asparagine, glutamine, particularly arginine or glutamine; residuecorresponding to X198 is aspartic acid, glutamic acid, arginine, lysine,serine, threonine, asparagine, glutamine, glycine, methionine, alanine,valine, leucine, or isoleucine, particularly glycine, glutamic acid, orlysine; residue corresponding to X200 is an aspartic acid, glutamicacid, or proline, particularly proline. In some embodiments, the regionor domain corresponding to residues 90-211 can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, or 1-20 residue differences at other amino acid residues ascompared to the domain of a reference sequence based on SEQ ID NO:128,130, or 160. In some embodiments, the number of differences can be 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, or about 20 residuedifferences at other amino acid residues in the domain. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to the amino acidsequence corresponding to residues 90-211 of a reference sequence basedon SEQ ID NO:128, 130, or 160 with the preceding features.

In some embodiments, the ketoreductase polypeptides with a domain orregion corresponding to residues 90-211 and having the specifiedfeatures for residues X145 and X190 as described herein, can furtherinclude in the region or domain one or more features selected from thefollowing: residue corresponding to X94 is a non-polar or a polarresidue; residue corresponding to X108 is a hydrophilic, polar orconstrained residue; residue corresponding to X117 is a non-polar or apolar residue; residue corresponding to X152 is a non-polar, basic, orhydrophilic residue; residue corresponding to X194 is a constrained,basic, or polar residue; residue corresponding to X198 is an acidic,basic, hydrophilic, or non-polar residue; residue corresponding to X199is an acidic, aliphatic, or non-polar residue; residue corresponding toX200 is an acidic or constrained residue. In some embodiments, theregion or domain corresponding to residues 90-211 can have additionally1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15,1-16, 1-18, or 1-20 residue differences at other amino acid residues ascompared to the domain of a reference sequence based on SEQ ID NO:128,130, or 160. In some embodiments, the number of differences can be 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, or about 20 residuedifferences at other amino acid residues in the domain. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to the amino acidsequence corresponding to residues 90-211 of a reference sequence basedon SEQ ID NO:128, 130, or 160 with the preceding features.

In some embodiments, the ketoreductase polypeptides with a domain orregion corresponding to residues 90-211 and having the specifiedfeatures for residues X145 and X190 as described herein, can furtherinclude in the region or domain one or more features selected from thefollowing: residue corresponding to X94 is glycine, methionine, alanine,valine, leucine, isoleucine, serine, threonine, asparagine, orglutamine, particularly asparagine, glycine, or serine; residuecorresponding to X108 is arginine, lysine, serine, threonine,asparagine, glutamine, histidine, particularly histidine or serine;residue corresponding to X117 is glycine, methionine, alanine, valine,leucine, isoleucine, serine, threonine, asparagine, or glutamine,particularly serine; residue corresponding to X152 is glycine,methionine, valine, leucine, isoleucine, arginine, lysine, serinethreonine, asparagine, or glutamine, particularly methionine or lysine;residue corresponding to X194 is proline, arginine, lysine, serine,threonine, asparagine, glutamine, particularly arginine or glutamine;residue corresponding to X198 is aspartic acid, glutamic acid, arginine,lysine, serine, threonine, asparagine, glutamine, glycine, methionine,alanine, valine, leucine, or isoleucine, particularly glycine; residuecorresponding to X199 is an aspartic acid, glutamic acid, glycine,methionine, alanine, valine, leucine, or isoleucine, particularlyaspartic acid; residue corresponding to X200 is aspartic acid, glutamicacid, or proline, particularly proline. In some embodiments, the regionor domain corresponding to residues 90-211 can have additionally 1-2,1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-14, 1-15, 1-16,1-18, or 1-20 residue differences at other amino acid residues ascompared to the domain of a reference sequence based on SEQ ID NO:128,130, or 160. In some embodiments, the number of differences can be 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, or about 20 residuedifferences at other amino acid residues in the domain. In someembodiments, the differences comprise conservative mutations. In someembodiments, the ketoreductase polypeptide comprises an amino acidsequence with at least the preceding features, and wherein the aminoacid sequence has at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, or 99% identity as compared to the amino acidsequence corresponding to residues 90-211 of a reference sequence basedon SEQ ID NO:128, 130, or 160 with the preceding features.

In some embodiments, the ketoreductase polypeptide has a region thatcorresponds to residues 1-89 of the sequence formula of SEQ ID NO:161,162 or 163, in which the amino acid sequence has one or more of thefollowing features: residue corresponding to X3 is an acidic, polar, orhydrophilic residue; residue corresponding to X7 is a non-polar or polarresidue; residue corresponding to X17 is a non-polar, aliphatic or polarresidue; residue corresponding to X21 is a non-polar, aromatic, orhydrophobic residue; residue corresponding to X25 is an acidic,non-polar or polar residue; residue corresponding to X29 is an acidic,aliphatic or non-polar residue; residue corresponding to X40 is aconstrained, basic, or hydrophilic residue; residue corresponding to X42is an acidic or non-polar residue; residue corresponding to X53 is anon-polar or an acidic residue; residue corresponding to X75 is anacidic or polar residue.

In some embodiments, the ketoreductase polypeptide has a region thatcorresponds to residues 1-89 of the sequence formula of SEQ ID NO:161,162 or 163, in which the amino sequence of the domain or region has oneor more of the following features: residue corresponding to X3 isaspartic acid, glutamic acid, serine, threonine, asparagine, orglutamine, particularly asparagine; residue corresponding to X7 isglycine, methionine, alanine, valine, leucine, isoleucine, serine,threonine, asparagine, or glutamine, particularly serine; residuecorresponding to X17 is glycine, methionine, alanine, valine, leucine,isoleucine, serine, threonine, asparagine, or glutamine, particularlyglutamine; residue corresponding to X21 is glycine, methionine, alanine,valine, leucine, isoleucine, tyrosine, phenylalanine, or tryptophan,particularly phenylalanine; residue corresponding to X25 is asparticacid, glutamic acid, serine, threonine, asparagine, glutamine, glycine,methionine, alanine, valine, leucine, isoleucine, particularlythreonine; residue corresponding to X29 is aspartic acid, glutamineacid, glycine, methionine, alanine, valine, leucine, or isoleucine,particularly glycine or alanine; residue corresponding to X40 ishistidine, lysine, arginine, serine, threonine, asparagine, orglutamine, particularly arginine; residue corresponding to X42 isaspartic acid, glutamic acid, glycine, methionine, alanine, valine,leucine, or isoleucine, particularly glycine; residue corresponding toX53 is glycine, methionine, alanine, valine, leucine, isoleucine,aspartic acid, glutamic acid, particularly aspartic acid; residuecorresponding to X75 is aspartic acid, glutamic acid, serine, threonine,asparagine, or glutamine, particularly arginine.

In some embodiments, the ketoreductase polypeptide has a region thatcorresponds to residues 212-252 of the sequence formula of SEQ IDNO:161, 162 or 163, in which the amino acid sequence has one or more ofthe following features: residue corresponding to X223 is a non-polar oraliphatic residue; and residue corresponding to X250 is a polar ornon-polar residue.

In some embodiments, the ketoreductase polypeptide has a region thatcorresponds to residues 212-252 of the sequence formula of SEQ IDNO:161, 162 or 163, in which the amino acid sequence has one or more ofthe following features: residue corresponding to X223 is glycine,methionine, alanine, valine, leucine, or isoleucine, particularlyvaline; and residue corresponding to X250 is serine, threonine,asparagine, glutamine, glycine, methionine, alanine, valine, leucine,isoleucine, particularly isoleucine.

In some embodiments, the ketoreductase polypeptides of the disclosurecan comprise a having an amino acid sequence that is at least about 85%,86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identical to a region or domain of SEQ ID NO:128, 130, or 160, such asresidues 90-211, with the proviso that the residue corresponding to X145is serine and the residue corresponding to X190 is cysteine, and whereinthe amino acid sequence can have additionally one or more of thefollowing substitutions such that the polypeptide is further improved(e.g., with respect to stereoselectivity, enzymatic activity, and/orthermostability) over the wild-type L. kefir ketoreductase or anotherengineered ketoreductase (such as SEQ ID NO:8): 3→N, 7→5, 17→Q, 21→F,25→T, 29→A or G, 42→G, 53→D, 75→N, 95→L or M, 96→Q, 101→Q or G, 105→G,108→H or S, 112→D, 117→S, 127→R, 147→L, 152→M, 157→T, 163→L or I, 167→V,176→V, 194→R, 197→V or E, 198→K or E, 199→D, 200→P, 211→R, 223→V, and250→L.

In some embodiments, the ketoreductase polypeptides of the disclosurecan comprise a region having an amino acid sequence that is at leastabout 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%,98%, or 99% identical to a region or domain of SEQ ID NO:128, 130, or160, such as residues 90-211, wherein the amino acid sequence can haveadditionally one or more of the following substitutions such that thepolypeptide is further improved (e.g., with respect tostereoselectivity, enzymatic activity, and/or thermostability) over thewild-type L. kefir ketoreductase or another engineered ketoreductase(such as SEQ ID NO:8): 7→5, 17→Q, 96→Q, 108→H, 117→S, 152→M, 163→I,176→V, 198→K, 199→D, 211→R, and 223→V.

In some embodiments, the ketoreductases of the disclosure are subject toone or more of the following provisos: (1) specifically excluded arepolypeptides with the specific sequences selected from SEQ ID NO: 8, 44,46, 48, 164 and 165; (2) the amino acid sequence requires at residuecorresponding to X152 a basic or non-polar residue, particularlymethionine or lysine; (3) the amino acid sequence requires at residuecorresponding to X199 an acidic residue, particularly aspartic acid; and(4) the amino acid sequence requires at residue corresponding to X96 aglutamine.

In some embodiments, each of the improved engineered ketoreductaseenzymes described herein can comprise deletions of the polypeptidesdescribed herein. Thus, for each and every embodiment of theketoreductase polypeptides of the disclosure, the deletions can compriseone or more amino acids, 2 or more amino acids, 3 or more amino acids, 4or more amino acids, 5 or more amino acids, 6 or more amino acids, 8 ormore amino acids, 10 or more amino acids, 15 or more amino acids, or 20or more amino acids, up to 10% of the total number of amino acids, up to10% of the total number of amino acids, up to 20% of the total number ofamino acids, or up to 30% of the total number of amino acids of theketoreductase polypeptides, as long as the functional activity of theketoreductase activity is maintained. In some embodiments, the deletionscan comprise, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12,1-14, 1-15, 1-16, 1-18, 1-20, 1-22, 1-24, 1-25, 1-30, 1-35 or about 1-40amino acids. In some embodiments, the deletions can comprise deletionsof 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, or 1-20 amino acidresidues. In some embodiments, the number of deletions can be 1, 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 30, 35 orabout 40 amino acids. In some embodiments, the deletions can comprisedeletions of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18,or 20 amino acid residues.

As will be appreciated by the skilled art, the polypeptides describedherein are not restricted to the genetically encoded amino acids. Inaddition to the genetically encoded amino acids, the polypeptidesdescribed herein may be comprised, either in whole or in part, ofnaturally-occurring and/or synthetic non-encoded amino acids. Certaincommonly encountered non-encoded amino acids of which the polypeptidesdescribed herein may be comprised include, but are not limited to: theD-stereomers of the genetically-encoded amino acids;2,3-diaminopropionic acid (Dpr); α-aminoisobutyric acid (Aib);ε-aminohexanoic acid (Aha); δ-aminovaleric acid (Ava); N-methylglycineor sarcosine (MeGly or Sar); ornithine (Orn); citrulline (Cit);t-butylalanine (Bua); t-butylglycine (Bug); N-methylisoleucine (MeIle);phenylglycine (Phg); cyclohexylalanine (Cha); norleucine (Nle);naphthylalanine (Nal); 2-chlorophenylalanine (Ocf);3-chlorophenylalanine (Mcf); 4-chlorophenylalanine (Pcf);2-fluorophenylalanine (Off); 3-fluorophenylalanine (Mff);4-fluorophenylalanine (Pff); 2-bromophenylalanine (Obf);3-bromophenylalanine (Mbf); 4-bromophenylalanine (Pbf);2-methylphenylalanine (Omf); 3-methylphenylalanine (Mmf);4-methylphenylalanine (Pmf); 2-nitrophenylalanine (Onf);3-nitrophenylalanine (Mnf); 4-nitrophenylalanine (Pnf);2-cyanophenylalanine (Ocf); 3-cyanophenylalanine (Mcf);4-cyanophenylalanine (Pcf); 2-trifluoromethylphenylalanine (Otf);3-trifluoromethylphenylalanine (Mtf); 4-trifluoromethylphenylalanine(Ptf); 4-aminophenylalanine (Paf); 4-iodophenylalanine (Pif);4-aminomethylphenylalanine (Pamf); 2,4-dichlorophenylalanine (Opef);3,4-dichlorophenylalanine (Mpcf); 2,4-difluorophenylalanine (Opff);3,4-difluorophenylalanine (Mpff); pyrid-2-ylalanine (2pAla);pyrid-3-ylalanine (3pAla); pyrid-4-ylalanine (4pAla); naphth-1-ylalanine(1nAla); naphth-2-ylalanine (2nAla); thiazolylalanine (taAla);benzothienylalanine (bAla); thienylalanine (tAla); furylalanine (fAla);homophenylalanine (hPhe); homotyrosine (hTyr); homotryptophan (hTrp);pentafluorophenylalanine (5ff); styrylkalanine (sAla); authrylalanine(aAla); 3,3-diphenylalanine (Dfa); 3-amino-5-phenypentanoic acid (Afp);penicillamine (Pen); 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid(Tic); β-2-thienylalanine (Thi); methionine sulfoxide (Mso);N(w)-nitroarginine (nArg); homolysine (hLys);phosphonomethylphenylalanine (pmPhe); phosphoserine (pSer);phosphothreonine (pThr); homoaspartic acid (hAsp); homoglutanic acid(hGlu); 1-aminocyclopent-(2 or 3)-ene-4 carboxylic acid; pipecolic acid(PA), azetidine-3-carboxylic acid (ACA);1-aminocyclopentane-3-carboxylic acid; allylglycine (aOly);propargylglycine (pgGly); homoalanine (hAla); norvaline (nVal);homoleucine (hLeu), homovaline (hVal); homoisolencine (hIle);homoarginine (hArg); N-acetyl lysine (AcLys); 2,4-diaminobutyric acid(Dbu); 2,3-diaminobutyric acid (Dab); N-methylvaline (MeVal);homocysteine (hCys); homoserine (hSer); hydroxyproline (Hyp) andhomoproline (hPro). Additional non-encoded amino acids of which thepolypeptides described herein may be comprised will be apparent to thoseof skill in the art (see, e.g., the various amino acids provided inFasman, 1989, CRC Practical Handbook of Biochemistry and MolecularBiology, CRC Press, Boca Raton, Fla., at pp. 3-70 and the referencescited therein, all of which are incorporated by reference). These aminoacids may be in either the L- or D-configuration.

Those of skill in the art will recognize that amino acids or residuesbearing side chain protecting groups may also comprise the polypeptidesdescribed herein. Non-limiting examples of such protected amino acids,which in this case belong to the aromatic category, include (protectinggroups listed in parentheses), but are not limited to: Arg(tos),Cys(methylbenzyl), Cys (nitropyridinesulfenyl), Glu(δ-benzylester),Gln(xanthyl), Asn(N-δ-xanthyl), His(bom), His(benzyl), His(tos),Lys(fmoc), Lys(tos), Ser(O-benzyl), Thr (O-benzyl) and Tyr(O-benzyl).

Non-encoding amino acids that are conformationally constrained of whichthe polypeptides described herein may be composed include, but are notlimited to, N-methyl amino acids (L-configuration); 1-aminocyclopent-(2or 3)-ene-4-carboxylic acid; pipecolic acid; azetidine-3-carboxylicacid; homoproline (hPro); and 1-aminocyclopentane-3-carboxylic acid.

As described above the various modifications introduced into thenaturally occurring polypeptide to generate an engineered ketoreductaseenzyme can be targeted to a specific property of the enzyme.

6.3 Polynucleotides Encoding Engineered Ketoreductases

In another aspect, the present disclosure provides polynucleotidesencoding the engineered ketoreductase enzymes disclosed herein. Thepolynucleotides may be operatively linked to one or more heterologousregulatory sequences that control gene expression to create arecombinant polynucleotide capable of expressing the polypeptide.Expression constructs containing a heterologous polynucleotide encodingthe engineered ketoreductase can be introduced into appropriate hostcells to express the corresponding ketoreductase polypeptide.

Because of the knowledge of the codons corresponding to the variousamino acids, availability of a protein sequence provides a descriptionof all the polynucleotides capable of encoding the subject. Thedegeneracy of the genetic code, where the same amino acids are encodedby alternative or synonymous codons allows an extremely large number ofnucleic acids to be made, all of which encode the improved ketoreductaseenzymes disclosed herein. Thus, having identified a particular aminoacid sequence, those skilled in the art could make any number ofdifferent nucleic acids by simply modifying the sequence of one or morecodons in a way which does not change the amino acid sequence of theprotein. In this regard, the present disclosure specificallycontemplates each and every possible variation of polynucleotides thatcould be made by selecting combinations based on the possible codonchoices, and all such variations are to be considered specificallydisclosed for any polypeptide disclosed herein, including the amino acidsequences presented in Tables 3 and 4.

In some embodiments, the polynucleotides encode a ketoreductasepolypeptides having at least the following features as compared to theamino acid sequence of SEQ ID NO:2, SEQ ID NO:4, or SEQ ID NO:158: (1)the amino acid residue corresponding to residue X145 is a serineresidue, and (2) the amino acid residue corresponding to residue X190 isa cysteine residue. In some embodiments, the polynucleotide comprises anucleotide sequence encoding a ketoreductase polypeptide with an aminoacid sequence that has at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%,92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% or more sequence identity toany of the reference engineered ketoreductase polypeptides describedherein, where the ketoreductase polypeptide comprises an amino acidsequence that has at least the following features: an amino acid residuecorresponding to residue position of 145 of SEQ ID NO:2, 4, or 158 isserine and the amino acid residue corresponding to residue position 190of SEQ ID NO:2, 4 or 158 is cysteine.

In some embodiments, the polynucleotides encode the polypeptidesdescribed herein but have at least about 85%, 86%, 87%, 88%, 89%, 90%,91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% or more sequence identityat the nucleotide level to a reference polynucleotide encoding anengineered ketoreductase. In some embodiments, the referencepolynucleotide is selected from polynucleotide sequences represented bySEQ ID NO: 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69,71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103,105, 107, 109, 111, 113, 115, 117, 119, 121, 123, and 125.

In some embodiments, the polynucleotide can encode an improvedketoreductase comprising an amino acid sequence that is at least about85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or99% identical to the amino acid sequence corresponding to SEQ ID NO: 42,44, 46, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80,82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112,114, 116, 118, 120, 122, 124, and 126 as listed in Tables 3 and 4,wherein the improved ketoreductase polypeptide amino acid sequenceincludes any one set of the specified amino acid substitutioncombinations presented in Tables 3 and 4. In some embodiments, thepolynucleotides encode an engineered ketoreductase polypeptidecomprising an amino acid sequence selected from SEQ ID NO: 42, 44, 46,50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84,86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116,118, 120, 122, 124, and 126.

In some embodiments, the polynucleotides are capable of hybridizingunder highly stringent conditions to a polynucleotide comprising SEQ IDNO: 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73,75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107,109, 111, 113, 115, 117, 119, 121, 123, and 125, where thepolynucleotides encode a functional ketoreductase carrying out theconversion of substrate to product as described herein.

In various embodiments, the codons are preferably selected to fit thehost cell in which the protein is being produced. For example, preferredcodons used in bacteria are used to express the gene in bacteria;preferred codons used in yeast are used for expression in yeast; andpreferred codons used in mammals are used for expression in mammaliancells. By way of example, the polynucleotide of SEQ ID NO: 3 has beencodon optimized for expression in E. coli, but otherwise encodes thenaturally occurring ketoreductase of Lactobacillus kefir.

In certain embodiments, all codons need not be replaced to optimize thecodon usage of the ketoreductases since the natural sequence willcomprise preferred codons and because use of preferred codons may not berequired for all amino acid residues. Consequently, codon optimizedpolynucleotides encoding the ketoreductase enzymes may contain preferredcodons at about 40%, 50%, 60%, 70%, 80%, or greater than 90% of codonpositions of the full length coding region.

In various embodiments, an isolated polynucleotide encoding an improvedketoreductase polypeptide may be manipulated in a variety of ways toprovide for expression of the polypeptide. Manipulation of the isolatedpolynucleotide prior to its insertion into a vector may be desirable ornecessary depending on the expression vector. The techniques formodifying polynucleotides and nucleic acid sequences utilizingrecombinant DNA methods are well known in the art. Guidance is providedin Sambrook et al., 2001, Molecular Cloning: A Laboratory Manual, 3^(rd)Ed., Cold Spring Harbor Laboratory Press; and Current Protocols inMolecular Biology, Ausubel. F. ed., Greene Pub. Associates, 1998,updates to 2006.

For bacterial host cells, suitable promoters for directing transcriptionof the nucleic acid constructs of the present disclosure, include thepromoters obtained from the E. coli lac operon, Streptomyces coelicoloragarase gene (dagA), Bacillus subtilis levansucrase gene (sacB),Bacillus licheniformis alpha-amylase gene (amyL), Bacillusstearothermophilus maltogenic amylase gene (amyM), Bacillusamyloliquefaciens alpha-amylase gene (amyQ), Bacillus licheniformispenicillinase gene (penP), Bacillus subtilis xylA and xylB genes, andprokaryotic beta-lactamase gene (Villa-Kamaroff et al., 1978, Proc. NatlAcad. Sci. USA 75: 3727-3731), as well as the tac promoter (DeBoer etal., 1983, Proc. Natl Acad. Sci. USA 80: 21-25).

For filamentous fungal host cells, suitable promoters for directing thetranscription of the nucleic acid constructs of the present disclosureinclude promoters obtained from the genes for Aspergillus oryzae TAKAamylase, Rhizomucor miehei aspartic proteinase, Aspergillus nigerneutral alpha-amylase, Aspergillus niger acid stable alpha-amylase,Aspergillus niger or Aspergillus awamori glucoamylase (glaA), Rhizomucormiehei lipase, Aspergillus oryzae alkaline protease, Aspergillus oryzaetriose phosphate isomerase, Aspergillus nidulans acetamidase, andFusarium oxysporum trypsin-like protease (WO 96/00787), as well as theNA2-tpi promoter (a hybrid of the promoters from the genes forAspergillus niger neutral alpha-amylase and Aspergillus oryzae triosephosphate isomerase), and mutant, truncated, and hybrid promotersthereof.

In a yeast host, useful promoters can be from the genes forSaccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiaegalactokinase (GAL1), Saccharomyces cerevisiae alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP), andSaccharomyces cerevisiae 3-phosphoglycerate kinase. Other usefulpromoters for yeast host cells are described by Romanos et al., 1992,Yeast 8:423-488.

The control sequence may also be a suitable transcription terminatorsequence, a sequence recognized by a host cell to terminatetranscription. The terminator sequence is operably linked to the 3′terminus of the nucleic acid sequence encoding the polypeptide. Anyterminator which is functional in the host cell of choice may be used inthe present invention.

For example, exemplary transcription terminators for filamentous fungalhost cells can be obtained from the genes for Aspergillus oryzae TAKAamylase, Aspergillus niger glucoamylase, Aspergillus nidulansanthranilate synthase, Aspergillus niger alpha-glucosidase, and Fusariumoxysporum trypsin-like protease.

Exemplary terminators for yeast host cells can be obtained from thegenes for Saccharomyces cerevisiae enolase, Saccharomyces cerevisiaecytochrome C (CYC1), and Saccharomyces cerevisiaeglyceraldehyde-3-phosphate dehydrogenase. Other useful terminators foryeast host cells are described by Romanos et al., 1992, supra.

The control sequence may also be a suitable leader sequence, anontranslated region of an mRNA that is important for translation by thehost cell. The leader sequence is operably linked to the 5′ terminus ofthe nucleic acid sequence encoding the polypeptide. Any leader sequencethat is functional in the host cell of choice may be used. Exemplaryleaders for filamentous fungal host cells are obtained from the genesfor Aspergillus oryzae TAKA amylase and Aspergillus nidulans triosephosphate isomerase. Suitable leaders for yeast host cells are obtainedfrom the genes for Saccharomyces cerevisiae enolase (ENO-1),Saccharomyces cerevisiae 3-phosphoglycerate kinase, Saccharomycescerevisiae alpha-factor, and Saccharomyces cerevisiae alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP).

The control sequence may also be a polyadenylation sequence, a sequenceoperably linked to the 3′ terminus of the nucleic acid sequence andwhich, when transcribed, is recognized by the host cell as a signal toadd polyadenosine residues to transcribed mRNA. Any polyadenylationsequence which is functional in the host cell of choice may be used inthe present invention. Exemplary polyadenylation sequences forfilamentous fungal host cells can be from the genes for Aspergillusoryzae TAKA amylase, Aspergillus niger glucoamylase, Aspergillusnidulans anthranilate synthase, Fusarium oxysporum trypsin-likeprotease, and Aspergillus niger alpha-glucosidase. Usefulpolyadenylation sequences for yeast host cells are described by Guo andSherman, 1995, Mol Cell Bio 15:5983-5990.

The control sequence may also be a signal peptide coding region thatcodes for an amino acid sequence linked to the amino terminus of apolypeptide and directs the encoded polypeptide into the cell'ssecretory pathway. The 5′ end of the coding sequence of the nucleic acidsequence may inherently contain a signal peptide coding region naturallylinked in translation reading frame with the segment of the codingregion that encodes the secreted polypeptide. Alternatively, the 5′ endof the coding sequence may contain a signal peptide coding region thatis foreign to the coding sequence. The foreign signal peptide codingregion may be required where the coding sequence does not naturallycontain a signal peptide coding region.

Alternatively, the foreign signal peptide coding region may simplyreplace the natural signal peptide coding region in order to enhancesecretion of the polypeptide. However, any signal peptide coding regionwhich directs the expressed polypeptide into the secretory pathway of ahost cell of choice may be used in the present invention.

Effective signal peptide coding regions for bacterial host cells are thesignal peptide coding regions obtained from the genes for Bacillus NC1B11837 maltogenic amylase, Bacillus stearothermophilus alpha-amylase,Bacillus licheniformis subtilisin, Bacillus licheniformisbeta-lactamase, Bacillus stearothermophilus neutral proteases (nprT,nprS, nprM), and Bacillus subtilis prsA. Further signal peptides aredescribed by Simonen and Palva, 1993, Microbiol Rev 57: 109-137.

Effective signal peptide coding regions for filamentous fungal hostcells can be the signal peptide coding regions obtained from the genesfor Aspergillus oryzae TAKA amylase, Aspergillus niger neutral amylase,Aspergillus niger glucoamylase, Rhizomucor miehei aspartic proteinase,Humicola insolens cellulase, and Humicola lanuginosa lipase.

Useful signal peptides for yeast host cells can be from the genes forSaccharomyces cerevisiae alpha-factor and Saccharomyces cerevisiaeinvertase. Other useful signal peptide coding regions are described byRomanos et al., 1992, supra.

The control sequence may also be a propeptide coding region that codesfor an amino acid sequence positioned at the amino terminus of apolypeptide. The resultant polypeptide is known as a proenzyme orpropolypeptide (or a zymogen in some cases). A propolypeptide isgenerally inactive and can be converted to a mature active polypeptideby catalytic or autocatalytic cleavage of the propeptide from thepropolypeptide. The propeptide coding region may be obtained from thegenes for Bacillus subtilis alkaline protease (aprE), Bacillus subtilisneutral protease (nprT), Saccharomyces cerevisiae alpha-factor,Rhizomucor miehei aspartic proteinase, and Myceliophthora thermophilalactase (WO 95/33836).

Where both signal peptide and propeptide regions are present at theamino terminus of a polypeptide, the propeptide region is positionednext to the amino terminus of a polypeptide and the signal peptideregion is positioned next to the amino terminus of the propeptideregion.

It may also be desirable to add regulatory sequences, which allow theregulation of the expression of the polypeptide relative to the growthof the host cell. Examples of regulatory systems are those which causethe expression of the gene to be turned on or off in response to achemical or physical stimulus, including the presence of a regulatorycompound. In prokaryotic host cells, suitable regulatory sequencesinclude the lac, tac, and trp operator systems. In yeast host cells,suitable regulatory systems include, as examples, the ADH2 system orGAL1 system. In filamentous fungi, suitable regulatory sequences includethe TAKA alpha-amylase promoter, Aspergillus niger glucoamylasepromoter, and Aspergillus oryzae gluco amylase promoter.

Other examples of regulatory sequences are those which allow for geneamplification. In eukaryotic systems, these include the dihydrofolatereductase gene, which is amplified in the presence of methotrexate, andthe metallothionein genes, which are amplified with heavy metals. Inthese cases, the nucleic acid sequence encoding the KRED polypeptide ofthe present invention would be operably linked with the regulatorysequence.

Thus, in another embodiment, the present disclosure is also directed toa recombinant expression vector comprising a polynucleotide encoding anengineered ketoreductase polypeptide or a variant thereof, and one ormore expression regulating regions such as a promoter and a terminator,a replication origin, etc., depending on the type of hosts into whichthey are to be introduced. The various nucleic acid and controlsequences described above may be joined together to produce arecombinant expression vector which may include one or more convenientrestriction sites to allow for insertion or substitution of the nucleicacid sequence encoding the polypeptide at such sites. Alternatively, thenucleic acid sequence of the present disclosure may be expressed byinserting the nucleic acid sequence or a nucleic acid constructcomprising the sequence into an appropriate vector for expression. Increating the expression vector, the coding sequence is located in thevector so that the coding sequence is operably linked with theappropriate control sequences for expression.

The recombinant expression vector may be any vector (e.g., a plasmid orvirus), which can be conveniently subjected to recombinant DNAprocedures and can bring about the expression of the polynucleotidesequence. The choice of the vector will typically depend on thecompatibility of the vector with the host cell into which the vector isto be introduced. The vectors may be linear or closed circular plasmids.

The expression vector may be an autonomously replicating vector, i.e., avector that exists as an extrachromosomal entity, the replication ofwhich is independent of chromosomal replication, e.g., a plasmid, anextrachromosomal element, a minichromosome, or an artificial chromosome.The vector may contain any means for assuring self-replication.Alternatively, the vector may be one which, when introduced into thehost cell, is integrated into the genome and replicated together withthe chromosome(s) into which it has been integrated. Furthermore, asingle vector or plasmid or two or more vectors or plasmids whichtogether contain the total DNA to be introduced into the genome of thehost cell, or a transposon may be used.

The expression vector of the present invention preferably contains oneor more selectable markers, which permit easy selection of transformedcells. A selectable marker is a gene the product of which provides forbiocide or viral resistance, resistance to heavy metals, prototrophy toauxotrophs, and the like. Examples of bacterial selectable markers arethe dal genes from Bacillus subtilis or Bacillus licheniformis, ormarkers, which confer antibiotic resistance such as ampicillin,kanamycin, chloramphenicol (Example 1) or tetracycline resistance.Suitable markers for yeast host cells are ADE2, HIS3, LEU2, LYS2, MET3,TRP1, and URA3.

Selectable markers for use in a filamentous fungal host cell include,but are not limited to, amdS (acetamidase), argB (ornithinecarbamoyltransferase), bar (phosphinothricin acetyltransferase), hph(hygromycin phosphotransferase), niaD (nitrate reductase), pyrG(orotidine-5′-phosphate decarboxylase), sC (sulfate adenyltransferase),and trpC (anthranilate synthase), as well as equivalents thereof.Embodiments for use in an Aspergillus cell include the amdS and pyrGgenes of Aspergillus nidulans or Aspergillus oryzae and the bar gene ofStreptomyces hygroscopicus.

The expression vectors of the present invention preferably contain anelement(s) that permits integration of the vector into the host cell'sgenome or autonomous replication of the vector in the cell independentof the genome. For integration into the host cell genome, the vector mayrely on the nucleic acid sequence encoding the polypeptide or any otherelement of the vector for integration of the vector into the genome byhomologous or nonhomologous recombination.

Alternatively, the expression vector may contain additional nucleic acidsequences for directing integration by homologous recombination into thegenome of the host cell. The additional nucleic acid sequences enablethe vector to be integrated into the host cell genome at a preciselocation(s) in the chromosome(s). To increase the likelihood ofintegration at a precise location, the integrational elements shouldpreferably contain a sufficient number of nucleic acids, such as 100 to10,000 base pairs, preferably 400 to 10,000 base pairs, and mostpreferably 800 to 10,000 base pairs, which are highly homologous withthe corresponding target sequence to enhance the probability ofhomologous recombination. The integrational elements may be any sequencethat is homologous with the target sequence in the genome of the hostcell. Furthermore, the integrational elements may be non-encoding orencoding nucleic acid sequences. On the other hand, the vector may beintegrated into the genome of the host cell by non-homologousrecombination.

For autonomous replication, the vector may further comprise an origin ofreplication enabling the vector to replicate autonomously in the hostcell in question. Examples of bacterial origins of replication are P15Aori (as shown in the plasmid of FIG. 5) or the origins of replication ofplasmids pBR322, pUC19, pACYC177 (which plasmid has the P15A ori), orpACYC184 permitting replication in E. coli, and pUB110, pE194, pTA1060,or pAMβ1 permitting replication in Bacillus. Examples of origins ofreplication for use in a yeast host cell are the 2 micron origin ofreplication, ARS1, ARS4, the combination of ARS1 and CEN3, and thecombination of ARS4 and CEN6. The origin of replication may be onehaving a mutation which makes it's functioning temperature-sensitive inthe host cell (see, e.g., Ehrlich, 1978, Proc Natl Acad Sci. USA75:1433).

More than one copy of a nucleic acid sequence of the present inventionmay be inserted into the host cell to increase production of the geneproduct. An increase in the copy number of the nucleic acid sequence canbe obtained by integrating at least one additional copy of the sequenceinto the host cell genome or by including an amplifiable selectablemarker gene with the nucleic acid sequence where cells containingamplified copies of the selectable marker gene, and thereby additionalcopies of the nucleic acid sequence, can be selected for by cultivatingthe cells in the presence of the appropriate selectable agent.

Many of the expression vectors for use in the present invention arecommercially available. Suitable commercial expression vectors includep3xFLAGTM™ expression vectors from Sigma-Aldrich Chemicals, St. LouisMo., which includes a CMV promoter and hGH polyadenylation site forexpression in mammalian host cells and a pBR322 origin of replicationand ampicillin resistance markers for amplification in E. coli. Othersuitable expression vectors are pBluescriptII SK(−) and pBK-CMV, whichare commercially available from Stratagene, LaJolla Calif., and plasmidswhich are derived from pBR322 (Gibco BRL), pUC (Gibco BRL), pREP4, pCEP4(Invitrogen) or pPoly (Lathe et al., 1987, Gene 57:193-201).

6.4 Host Cells for Expression of Ketoreductase Polypeptides

In another aspect, the present disclosure provides a host cellcomprising a polynucleotide encoding an improved ketoreductasepolypeptide of the present disclosure, the polynucleotide beingoperatively linked to one or more control sequences for expression ofthe ketoreductase enzyme in the host cell. Host cells for use inexpressing the KRED polypeptides encoded by the expression vectors ofthe present invention are well known in the art and include but are notlimited to, bacterial cells, such as E. coli, Lactobacillus kefir,Lactobacillus brevis, Lactobacillus minor, Streptomyces and Salmonellatyphimurium cells; fungal cells, such as yeast cells (e.g.,Saccharomyces cerevisiae or Pichia pastoris (ATCC Accession No.201178)); insect cells such as Drosophila S2 and Spodoptera Sf9 cells;animal cells such as CHO, COS, BHK, 293, and Bowes melanoma cells; andplant cells. Appropriate culture mediums and growth conditions for theabove-described host cells are well known in the art.

Polynucleotides for expression of the ketoreductase may be introducedinto cells by various methods known in the art. Techniques include amongothers, electroporation, biolistic particle bombardment, liposomemediated transfection, calcium chloride transfection, and protoplastfusion. Various methods for introducing polynucleotides into cells willbe apparent to the skilled artisan.

An exemplary host cell is Escherichia coli W3110. The expression vectorwas created by operatively linking a polynucleotide encoding an improvedketoreductase into the plasmid pCK110900 operatively linked to the lacpromoter under control of the lacI repressor. The expression vector alsocontained the P15a origin of replication and the chloramphenicolresistance gene. Cells containing the subject polynucleotide inEscherichia coli W3110 were isolated by subjecting the cells tochloramphenicol selection.

6.5 Methods of Generating Engineered Ketoreductase Polypeptides

In some embodiments, to make the improved KRED polynucleotides andpolypeptides of the present disclosure, the naturally-occurringketoreductase enzyme that catalyzes the reduction reaction is obtained(or derived) from Lactobacillus kefir or Lactobacillus brevis. In someembodiments, the parent polynucleotide sequence is codon optimized toenhance expression of the ketoreductase in a specified host cell. As anillustration, the parental polynucleotide sequence encoding thewild-type KRED polypeptide of Lactobacillus kefir was constructed fromoligonucleotides prepared based upon the known polypeptide sequence ofLactobacillus kefir KRED sequence available in Genbank database (Genbankaccession no. AAP94029 GI:33112056). The parental polynucleotidesequence, designated as SEQ ID NO: 3, was codon optimized for expressionin E. coli and the codon-optimized polynucleotide cloned into anexpression vector, placing the expression of the ketoreductase geneunder the control of the lac promoter and lacI repressor gene. Clonesexpressing the active ketoreductase in E. coli were identified and thegenes sequenced to confirm their identity. The sequence designated (SEQID NO: 3) was the parent sequence utilized as the starting point formost experiments and library construction of engineered ketoreductasesevolved from the Lactobacillus kefir ketoreductase.

The engineered ketoreductases can be obtained by subjecting thepolynucleoticde encoding the naturally occurring ketoreductase tomutagenesis and/or directed evolution methods, as discussed above. Anexemplary directed evolution technique is mutagenesis and/or DNAshuffling as described in Stemmer, 1994, Proc Natl Acad Sci USA91:10747-10751; WO 95/22625; WO 97/0078; WO 97/35966; WO 98/27230; WO00/42651; WO 01/75767 and U.S. Pat. No. 6,537,746. Other directedevolution procedures that can be used include, among others, staggeredextension process (StEP), in vitro recombination (Zhao et al., 1998,Nat. Biotechnol. 16:258-261), mutagenic PCR (Caldwell et al., 1994, PCRMethods Appl. 3:S136-S140), and cassette mutagenesis (Black et al.,1996, Proc Natl Acad Sci USA 93:3525-3529).

The clones obtained following mutagenesis treatment are screened forengineered ketoreductases having a desired improved enzyme property.Measuring enzyme activity from the expression libraries can be performedusing the standard biochemistry technique of monitoring the rate ofdecrease (via a decrease in absorbance or fluorescence) of NADH or NADPHconcentration, as it is converted into NAD or NADP⁺. In this reaction,the NADH or NADPH is consumed (oxidized) by the ketoreductase as theketoreductase reduces a ketone substrate to the corresponding hydroxylgroup. The rate of decrease of NADH or NADPH concentration, as measuredby the decrease in absorbance or fluorescence, per unit time indicatesthe relative (enzymatic) activity of the KRED polypeptide in a fixedamount of the lysate (or a lyophilized powder made therefrom). Where theimproved enzyme property desired is thermal stability, enzyme activitymay be measured after subjecting the enzyme preparations to a definedtemperature and measuring the amount of enzyme activity remaining afterheat treatments. Clones containing a polynucleotide encoding aketoreductase are then isolated, sequenced to identify the nucleotidesequence changes (if any), and used to express the enzyme in a hostcell.

Where the sequence of the engineered polypeptide is known, thepolynucleotides encoding the enzyme can be prepared by standardsolid-phase methods, according to known synthetic methods. In someembodiments, fragments of up to about 100 bases can be individuallysynthesized, then joined (e.g., by enzymatic or chemical litigationmethods, or polymerase mediated methods) to form any desired continuoussequence. For example, polynucleotides and oligonucleotides of theinvention can be prepared by chemical synthesis using, e.g., theclassical phosphoramidite method described by Beaucage et al., 1981, TetLett 22:1859-69, or the method described by Matthes et al., 1984, EMBOJ. 3:801-05, e.g., as it is typically practiced in automated syntheticmethods. According to the phosphoramidite method, oligonucleotides aresynthesized, e.g., in an automatic DNA synthesizer, purified, annealed,ligated and cloned in appropriate vectors. In addition, essentially anynucleic acid can be obtained from any of a variety of commercialsources, such as The Midland Certified Reagent Company, Midland, Tex.,The Great American Gene Company, Ramona, Calif., ExpressGen Inc.Chicago, Ill., Operon Technologies Inc., Alameda, Calif., and manyothers.

Engineered ketoreductase enzymes expressed in a host cell can berecovered from the cells and or the culture medium using any one or moreof the well known techniques for protein purification, including, amongothers, lysozyme treatment, sonication, filtration, salting-out,ultra-centrifugation, and chromatography. Suitable solutions for lysingand the high efficiency extraction of proteins from bacteria, such as E.coli, are commercially available under the trade name CelLytic B™ fromSigma-Aldrich of St. Louis Mo.

Chromatographic techniques for isolation of the ketoreductasepolypeptide include, among others, reverse phase chromatography highperformance liquid chromatography, ion exchange chromatography, gelelectrophoresis, and affinity chromatography. Conditions for purifying aparticular enzyme will depend, in part, on factors such as net charge,hydrophobicity, hydrophilicity, molecular weight, molecular shape, etc.,and will be apparent to those having skill in the art.

In some embodiments, affinity techniques may be used to isolate theimproved ketoreductase enzymes. For affinity chromatographypurification, any antibody which specifically binds the ketoreductasepolypeptide may be used. For the production of antibodies, various hostanimals, including but not limited to rabbits, mice, rats, etc., may beimmunized by injection with a compound. The compound may be attached toa suitable carrier, such as BSA, by means of a side chain functionalgroup or linkers attached to a side chain functional group. Variousadjuvants may be used to increase the immunological response, dependingon the host species, including but not limited to Freund's (complete andincomplete), mineral gels such as aluminum hydroxide, surface activesubstances such as lysolecithin, pluronic polyols, polyanions, peptides,oil emulsions, keyhole limpet hemocyanin, dinitrophenol, and potentiallyuseful human adjuvants such as BCG (bacilli Calmette Guerin) andCorynebacterium parvum.

6.6 Methods of Using the Engineered Ketoreductase Enzymes and CompoundsPrepared Therewith

The ketoreductase enzymes described herein can catalyze the reduction ofthe substrate compound of structural formula (I) (5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione:

to the corresponding stereosiomeric product of structural formula (II)((4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one):

In some embodiments, the method for reducing the substrate having thechemical formula (I) to the corresponding product of formula (II)comprises contacting or incubating the substrate with a ketoreductasepolypeptides disclosed herein under reaction conditions suitable forreducing or converting the substrate to the product compound. Theproduct in an intermediate for the synthesis of Ezetimibe, ananti-hyperlipidemic drug for lowering cholesterol levels (U.S. Pat. No.5,767,115). Thus, in a method for synthesizing Ezetimibe, the method cancomprise a step in which the compound of formula (I) is converted to thecompound of formula (II) using a ketoreductase polypeptide disclosedherein. In some embodiments, the product in greater than about 99%,99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8% or 99.9%stereomeric excess over the corresponding (R) alcohol product.

In some embodiments, the ketoreductase enzymes described herein are alsocapable of catalyzing the reduction reaction of the keto group in thecompound of structural formula (III),1-(4-fluorophenyl)-3(R)-[3-oxo-3-(4-fluorophenyl)propyl)]-4(S)-(4-hydroxyphenyl)-2-azetidinone,

to the corresponding stereoisomeric alcohol product of structuralformula (IV),1-(4-fluorophenyl)-3(R)-[3(S)-hydroxy-3(4-fluorophenyl)-propyl)]-4(S)-(4-hydroxyphenyl)-2-azetidinone(i.e., Ezetimibe):

Thus, the present disclosure provides a method of synthesizingEzetimibe, the method comprising contacting or incubating the compoundof formula (III) with a ketoreductase polypeptide disclosed herein underreaction conditions suitable for reducing or converting the substratecompound of formula (III) to the production compound of formula (IV).Other compounds similar to the compounds of formula (I) and compounds offormula (III) are described in U.S. Pat. No. 5,767,115 (incorporatedherein by reference).

In the method for reducing the compound of formula (I) to the compoundof formula (II), or for reducing the compound of formula (III) to thecompound of formula (IV), the ketoreductase polypeptides have, ascompared to the wild-type L. kefir, L. brevis, L. minor KRED sequencesof SEQ ID NO:4, 2, and 158, respectively, at least the following aminoacid substitutions: (1) residue 145 is serine and (2) residue 190 iscysteine. Various embodiments of the ketoreductase polypeptides aredescribed above. In some embodiments, as compared to the wild-type L.kefi, L. brevis, L. minor KRED sequences of SEQ ID NO:4, 2, and 158, theketoreductase polypeptides have at least the following amino acidsubstitutions: (1) residue 145 is a serine residue, (2) residue 190 is acysteine residue, and (3) residue 96 is a glutamine residue. In someembodiments, as compared to the wild-type L. kefi, L. brevis, L. minorKRED sequences of SEQ ID NO:4, 2, and 158, the ketoreductasepolypeptides of the invention have at least the following amino acidsubstitutions: (1) residue X145 is a serine residue, (2) residue X190 isa cysteine residue, and (3) residue X211 is an arginine residue.

As noted herein, in some embodiments, the ketoreductase polypeptides cancomprise an amino acid sequence that is at least about 85%, 86%, 87%,88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identicalas compared a reference sequence comprising the sequence of SEQ IDNO:128, 130, or 160, with the proviso that the polypeptide comprises anamino acid sequence in which the amino acid residue corresponding toresidue X145 is a serine, and the amino acid residue corresponding toresidue X190 is a cysteine. In some embodiments, these ketoreductasepolypeptides can have one or more modifications to the amino acidsequence of SEQ ID NO:128, 130 or 160. The modifications can includesubstitutions, deletions, and insertions. The substitutions can benon-conservative substitutions, conservative substitutions, or acombination of non-conservative and conservative substitutions.

In some embodiments of the method for reducing the substrate to theproduct, the substrate is reduced to the product in greater than about99% stereomeric excess, wherein the ketoreductase polypeptide comprisesa sequence that corresponds to SEQ ID NO: SEQ ID NO: 42, 44, 46, 48, 50,52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86,88, 90, 92, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118,120, 122, 124, and 126.

In another embodiment of this method for reducing the substrate to theproduct, at least about 95% of the substrate is converted to the productin less than about 24 hours when carried out with greater than about 100g/L of substrate and less than about 5 g/L of the polypeptide, whereinthe polypeptide comprises an amino acid sequence corresponding to SEQ IDNO:102, 108, 120, 122, 124, 126.

As is known by those of skill in the art, ketoreductase-catalyzedreduction reactions typically require a cofactor. Reduction reactionscatalyzed by the engineered ketoreductase enzymes described herein alsotypically require a cofactor, although many embodiments of theengineered ketoreductases require far less cofactor than reactionscatalyzed with wild-type ketoreductase enzymes. As used herein, the term“cofactor” refers to a non-protein compound that operates in combinationwith a ketoreductase enzyme. Cofactors suitable for use with theengineered ketoreductase enzymes described herein include, but are notlimited to, NADP (nicotinamide adenine dinucleotide phosphate), NADPH(the reduced form of NADP⁺), NAD (nicotinamide adenine dinucleotide) andNADH (the reduced form of NAD⁺). Generally, the reduced form of thecofactor is added to the reaction mixture. The reduced NAD(P)H form canbe optionally regenerated from the oxidized NAD(P)⁺ form using acofactor regeneration system.

The term “cofactor regeneration system” refers to a set of reactantsthat participate in a reaction that reduces the oxidized form of thecofactor (e.g., NADP⁺ to NADPH). Cofactors oxidized by theketoreductase-catalyzed reduction of the keto substrate are regeneratedin reduced form by the cofactor regeneration system. Cofactorregeneration systems comprise a stoichiometric reductant that is asource of reducing hydrogen equivalents and is capable of reducing theoxidized form of the cofactor. The cofactor regeneration system mayfurther comprise a catalyst, for example an enzyme catalyst thatcatalyzes the reduction of the oxidized form of the cofactor by thereductant. Cofactor regeneration systems to regenerate NADH or NADPHfrom NAD⁺ or NADP⁺, respectively, are known in the art and may be usedin the methods described herein.

Suitable exemplary cofactor regeneration systems that may be employedinclude, but are not limited to, glucose and glucose dehydrogenase,formate and formate dehydrogenase, glucose-6-phosphate andglucose-6-phosphate dehydrogenase, a secondary (e.g., isopropanol)alcohol and secondary alcohol dehydrogenase, phosphite and phosphitedehydrogenase, molecular hydrogen and hydrogenase, and the like. Thesesystems may be used in combination with either NADP⁺/NADPH or NAD⁺/NADHas the cofactor. Electrochemical regeneration using hydrogenase may alsobe used as a cofactor regeneration system. See, e.g., U.S. Pat. Nos.5,538,867 and 6,495,023, both of which are incorporated herein byreference. Chemical cofactor regeneration systems comprising a metalcatalyst and a reducing agent (for example, molecular hydrogen orformate) are also suitable. See, e.g., PCT publication WO 2000/053731,which is incorporated herein by reference.

The terms “glucose dehydrogenase” and “GDH” are used interchangeablyherein to refer to an NAD⁺ or NADP⁺-dependent enzyme that catalyzes theconversion of D-glucose and NAD⁺ or NADP⁺ to gluconic acid and NADH orNADPH, respectively. Equation (1), below, describes the glucosedehydrogenase-catalyzed reduction of NAD⁺ or NADP⁺ by glucose.

Glucose dehydrogenases that are suitable for use in the practice of themethods described herein include both naturally occurring glucosedehydrogenases, as well as non-naturally occurring glucosedehydrogenases. Naturally occurring glucose dehydrogenase encoding geneshave been reported in the literature. For example, the Bacillus subtilis61297 GDH gene was expressed in E. coli and was reported to exhibit thesame physicochemical properties as the enzyme produced in its nativehost (Vasantha et al., 1983, Proc. Natl. Acad. Sci. USA 80:785). Thegene sequence of the B. subtilis GDH gene, which corresponds to GenbankAcc. No. M12276, was reported by Lampel et al., 1986, J. Bacteriol.166:238-243, and in corrected form by Yamane et al., 1996, Microbiology142:3047-3056 as Genbank Acc. No. D50453. Naturally occurring GDH genesalso include those that encode the GDH from B. cereus ATCC 14579(Nature, 2003, 423:87-91; Genbank Acc. No. AE017013) and B. megaterium(Eur. J. Biochem., 1988, 174:485-490, Genbank Acc. No. X12370; J.Ferment. Bioeng., 1990, 70:363-369, Genbank Acc. No. GI216270). Glucosedehydrogenases from Bacillus sp. are provided in PCT publication WO2005/018579 as SEQ ID NOS: 10 and 12 (encoded by polynucleotidesequences corresponding to SEQ ID NOS: 9 and 11, respectively, of thePCT publication), the disclosure of which is incorporated herein byreference.

Non-naturally occurring glucose dehydrogenases may be generated usingknown methods, such as, for example, mutagenesis, directed evolution,and the like. GDH enzymes having suitable activity, whether naturallyoccurring or non-naturally occurring, may be readily identified usingthe assay described in Example 4 of PCT publication WO 2005/018579, thedisclosure of which is incorporated herein by reference. Exemplarynon-naturally occurring glucose dehydrogenases are provided in PCTpublication WO 2005/018579 as SEQ ID NOS: 62, 64, 66, 68, 122, 124, and126. The polynucleotide sequences that encode them are provided in PCTpublication WO 2005/018579 as SEQ ID NOS: 61, 63, 65, 67, 121, 123, and125, respectively. All of these sequences are incorporated herein byreference. Additional non-naturally occurring glucose dehydrogenasesthat are suitable for use in the ketoreductase-catalyzed reductionreactions disclosed herein are provided in U.S. application publicationNos. 2005/0095619 and 2005/0153417, the disclosures of which areincorporated herein by reference.

Glucose dehydrogenases employed in the ketoreductase-catalyzed reductionreactions described herein may exhibit an activity of at least about 10μmol/min/mg and sometimes at least about 10² μmol/min/mg or about 10³μmol/min/mg, up to about 10⁴ μmol/min/mg or higher in the assaydescribed in Example 4 of PCT publication WO 2005/018579.

The ketoreductase-catalyzed reduction reactions described herein aregenerally carried out in a solvent. Suitable solvents include water,organic solvents (e.g., ethyl acetate, butyl acetate, 1-octanol,heptane, octane, methyl t-butyl ether (MTBE), toluene, and the like),and ionic liquids (e.g., 1-ethyl 4-methylimidazolium tetrafluoroborate,1-butyl-3-methylimidazolium tetrafluoroborate,1-butyl-3-methylimidazolium hexafluorophosphate, and the like). In someembodiments, aqueous solvents, including water and aqueous co-solventsystems, are used.

Exemplary aqueous co-solvent systems have water and one or more organicsolvent. In general, an organic solvent component of an aqueousco-solvent system is selected such that it does not completelyinactivate the ketoreductase enzyme. Appropriate co-solvent systems canbe readily identified by measuring the enzymatic activity of thespecified engineered ketoreductase enzyme with a defined substrate ofinterest in the candidate solvent system, utilizing an enzyme activityassay, such as those described herein.

The organic solvent component of an aqueous co-solvent system may bemiscible with the aqueous component, providing a single liquid phase, ormay be partly miscible or immiscible with the aqueous component,providing two liquid phases. Generally, when an aqueous co-solventsystem is employed, it is selected to be biphasic, with water dispersedin an organic solvent, or vice-versa. Generally, when an aqueousco-solvent system is utilized, it is desirable to select an organicsolvent that can be readily separated from the aqueous phase. Ingeneral, the ratio of water to organic solvent in the co-solvent systemis typically in the range of from about 90:10 to about 10:90 (v/v)organic solvent to water, and between 80:20 and 20:80 (v/v) organicsolvent to water. The co-solvent system may be pre-formed prior toaddition to the reaction mixture, or it may be formed in situ in thereaction vessel.

The aqueous solvent (water or aqueous co-solvent system) may bepH-buffered or unbuffered. Generally, the reduction can be carried outat a pH of about 10 or below, usually in the range of from about 5 toabout 10. In some embodiments, the reduction is carried out at a pH ofabout 9 or below, usually in the range of from about 5 to about 9. Insome embodiments, the reduction is carried out at a pH of about 8 orbelow, often in the range of from about 5 to about 8, and usually in therange of from about 6 to about 8. The reduction may also be carried outat a pH of about 7.8 or below, or 7.5 or below. Alternatively, thereduction may be carried out a neutral pH, i.e., about 7.

During the course of the reduction reactions, the pH of the reactionmixture may change. The pH of the reaction mixture may be maintained ata desired pH or within a desired pH range by the addition of an acid ora base during the course of the reaction. Alternatively, the pH may becontrolled by using an aqueous solvent that comprises a buffer. Suitablebuffers to maintain desired pH ranges are known in the art and include,for example, phosphate buffer, triethanolamine buffer, and the like.Combinations of buffering and acid or base addition may also be used.

When the glucose/glucose dehydrogenase cofactor regeneration system isemployed, the co-production of gluconic acid (pKa=3.6), as representedin equation (1) causes the pH of the reaction mixture to drop if theresulting aqueous gluconic acid is not otherwise neutralized. The pH ofthe reaction mixture may be maintained at the desired level by standardbuffering techniques, wherein the buffer neutralizes the gluconic acidup to the buffering capacity provided, or by the addition of a baseconcurrent with the course of the conversion. Combinations of bufferingand base addition may also be used. Suitable buffers to maintain desiredpH ranges are described above. Suitable bases for neutralization ofgluconic acid are organic bases, for example amines, alkoxides and thelike, and inorganic bases, for example, hydroxide salts (e.g., NaOH),carbonate salts (e.g., NaHCO₃), bicarbonate salts (e.g., K₂CO₃), basicphosphate salts (e.g., K₂HPO₄, Na₃PO₄), and the like. The addition of abase concurrent with the course of the conversion may be done manuallywhile monitoring the reaction mixture pH or, more conveniently, by usingan automatic titrator as a pH stat. A combination of partial bufferingcapacity and base addition can also be used for process control.

When base addition is employed to neutralize gluconic acid releasedduring a ketoreductase-catalyzed reduction reaction, the progress of theconversion may be monitored by the amount of base added to maintain thepH. Typically, bases added to unbuffered or partially buffered reactionmixtures over the course of the reduction are added in aqueoussolutions.

In some embodiments, the co-factor regenerating system can comprises aformate dehydrogenase. The terms “formate dehydrogenase” and “FDH” areused interchangeably herein to refer to an NAD⁺ or NADP⁺-dependentenzyme that catalyzes the conversion of formate and NAD⁺ or NADP⁺ tocarbon dioxide and NADH or NADPH, respectively. Formate dehydrogenasesthat are suitable for use as cofactor regenerating systems in theketoreductase-catalyzed reduction reactions described herein includeboth naturally occurring formate dehydrogenases, as well asnon-naturally occurring formate dehydrogenases. Formate dehydrogenasesinclude those corresponding to SEQ ID NOS: 70 (Pseudomonas sp.) and 72(Candida boidinii) of PCT publication WO 2005/018579, which are encodedby polynucleotide sequences corresponding to SEQ ID NOS: 69 and 71,respectively, of PCT publication 2005/018579, the disclosures of whichare incorporated herein by reference. Formate dehydrogenases employed inthe methods described herein, whether naturally occurring ornon-naturally occurring, may exhibit an activity of at least about 1μmol/min/mg, sometimes at least about 10 μmol/min/mg, or at least about10² μmol/min/mg, up to about 10³ μmol/min/mg or higher, and can bereadily screened for activity in the assay described in Example 4 of PCTpublication WO 2005/018579.

As used herein, the term “formate” refers to formate anion (HCO₂ ⁻),formic acid (HCO₂H), and mixtures thereof. Formate may be provided inthe form of a salt, typically an alkali or ammonium salt (for example,HCO₂Na, KHCO₂NH₄, and the like), in the form of formic acid, typicallyaqueous formic acid, or mixtures thereof. Formic acid is a moderateacid. In aqueous solutions within several pH units of its pKa (pKa=3.7in water) formate is present as both HCO₂ ⁻ and HCO₂H in equilibriumconcentrations. At pH values above about pH 4, formate is predominantlypresent as HCO₂ ⁻. When formate is provided as formic acid, the reactionmixture is typically buffered or made less acidic by adding a base toprovide the desired pH, typically of about pH 5 or above. Suitable basesfor neutralization of formic acid include, but are not limited to,organic bases, for example amines, alkoxides and the like, and inorganicbases, for example, hydroxide salts (e.g., NaOH), carbonate salts (e.g.,NaHCO₃), bicarbonate salts (e.g., K₂CO₃), basic phosphate salts (e.g.,K₂HPO₄, Na₃PO₄), and the like.

For pH values above about pH 5, at which formate is predominantlypresent as HCO₂ ⁻, Equation (2) below, describes the formatedehydrogenase-catalyzed reduction of NAD⁺ or NADP⁺ by formate.

When formate and formate dehydrogenase are employed as the cofactorregeneration system, the pH of the reaction mixture may be maintained atthe desired level by standard buffering techniques, wherein the bufferreleases protons up to the buffering capacity provided, or by theaddition of an acid concurrent with the course of the conversion.Suitable acids to add during the course of the reaction to maintain thepH include organic acids, for example carboxylic acids, sulfonic acids,phosphonic acids, and the like, mineral acids, for example hydrohalicacids (such as hydrochloric acid), sulfuric acid, phosphoric acid, andthe like, acidic salts, for example dihydrogenphosphate salts (e.g.,KH₂PO₄), bisulfate salts (e.g., NaHSO₄) and the like. Some embodimentsutilize formic acid, whereby both the formate concentration and the pHof the solution are maintained.

When acid addition is employed to maintain the pH during a reductionreaction using the formate/formate dehydrogenase cofactor regenerationsystem, the progress of the conversion may be monitored by the amount ofacid added to maintain the pH. Typically, acids added to unbuffered orpartially buffered reaction mixtures over the course of conversion areadded in aqueous solutions.

The terms “secondary alcohol dehydrogenase” and “sADH” are usedinterchangeably herein to refer to an NAD⁺ or NADP⁺-dependent enzymethat catalyzes the conversion of a secondary alcohol and NAD⁺ or NADP⁺to a ketone and NADH or NADPH, respectively. Equation (3), below,describes the reduction of NAD⁺ or NADP⁺ by a secondary alcohol,illustrated by isopropanol.

Secondary alcohol dehydrogenases that are suitable for use as cofactorregenerating systems in the ketoreductase-catalyzed reduction reactionsdescribed herein include both naturally occurring secondary alcoholdehydrogenases, as well as non-naturally occurring secondary alcoholdehydrogenases. Naturally occurring secondary alcohol dehydrogenasesinclude known alcohol dehydrogenases from, Thermoanerobium brockii,Rhodococcus etythropolis, Lactobacillus kefir, Lactobacillus minor andLactobacillus brevis, and non-naturally occurring secondary alcoholdehydrogenases include engineered alcohol dehdyrogenases derivedtherefrom. Secondary alcohol dehydrogenases employed in the methodsdescribed herein, whether naturally occurring or non-naturallyoccurring, may exhibit an activity of at least about 1 μmol/min/mg,sometimes at least about 10 μmol/min/mg, or at least about 10²μmol/min/mg, up to about 10³ μmol/min/mg or higher.

Suitable secondary alcohols include lower secondary alkanols andaryl-alkyl carbinols. Examples of lower secondary alcohols includeisopropanol, 2-butanol, 3-methyl-2-butanol, 2-pentanol, 3-pentanol,3,3-dimethyl-2-butanol, and the like. In one embodiment the secondaryalcohol is isopropanol. Suitable aryl-akyl carbinols includeunsubstituted and substituted 1-arylethanols.

In one embodiment, where oxidation of isopropanol to acetone is used forregeneration of NADH/NADPH, the reaction may be run at reduced pressurein such a manner that the acetone is removed from the reaction mixture.

When a secondary alcohol and secondary alcohol dehydrogenase areemployed as the cofactor regeneration system, the resulting NAD⁺ orNADP⁺ is reduced by the coupled oxidation of the secondary alcohol tothe ketone by the secondary alcohol dehydrogenase. Some engineeredketoreductases also have activity to dehydrogenate a secondary alcoholreductant. In some embodiments using secondary alcohol as reductant, theengineered ketoreductase and the secondary alcohol dehydrogenase are thesame enzyme.

In carrying out embodiments of the ketoreductase-catalyzed reductionreactions described herein employing a cofactor regeneration system,either the oxidized or reduced form of the cofactor may be providedinitially. As described above, the cofactor regeneration system convertsoxidized cofactor to its reduced form, which is then utilized in thereduction of the ketoreductase substrate.

In some embodiments, cofactor regeneration systems are not used. Forreduction reactions carried out without the use of a cofactorregenerating systems, the cofactor is added to the reaction mixture inreduced form.

In some embodiments, when the process is carried out using whole cellsof the host organism, the whole cell may natively provide the cofactor.Alternatively or in combination, the cell may natively or recombinantlyprovide the glucose dehydrogenase.

In carrying out the stereoselective reduction reactions describedherein, the engineered ketoreductase enzyme, and any enzymes comprisingthe optional cofactor regeneration system, may be added to the reactionmixture in the form of the purified enzymes, whole cells transformedwith gene(s) encoding the enzymes, and/or cell extracts and/or lysatesof such cells. The gene(s) encoding the engineered ketoreductase enzymeand the optional cofactor regeneration enzymes can be transformed intohost cells separately or together into the same host cell. For example,in some embodiments one set of host cells can be transformed withgene(s) encoding the engineered ketoreductase enzyme and another set canbe transformed with gene(s) encoding the cofactor regeneration enzymes.Both sets of transformed cells can be utilized together in the reactionmixture in the form of whole cells, or in the form of lysates orextracts derived therefrom. In other embodiments, a host cell can betransformed with gene(s) encoding both the engineered ketoreductaseenzyme and the cofactor regeneration enzymes.

Whole cells transformed with gene(s) encoding the engineeredketoreductase enzyme and/or the optional cofactor regeneration enzymes,or cell extracts and/or lysates thereof, may be employed in a variety ofdifferent forms, including solid (e.g., lyophilized, spray-dried, andthe like) or semisolid (e.g., a crude paste).

The cell extracts or cell lysates may be partially purified byprecipitation (ammonium sulfate, polyethyleneimine, heat treatment orthe like, followed by a desalting procedure prior to lyophilization(e.g., ultrafiltration, dialysis, and the like). Any of the cellpreparations may be stabilized by crosslinking using known crosslinkingagents, such as, for example, glutaraldehyde or immobilization to asolid phase (e.g., Eupergit C, and the like).

The solid reactants (e.g., enzyme, salts, etc.) may be provided to thereaction in a variety of different forms, including powder (e.g.,lyophilized, spray dried, and the like), solution, emulsion, suspension,and the like. The reactants can be readily lyophilized or spray driedusing methods and equipment that are known to those having ordinaryskill in the art. For example, the protein solution can be frozen at−80° C. in small aliquots, then added to a prechilled lyophilizationchamber, followed by the application of a vacuum. After the removal ofwater from the samples, the temperature is typically raised to 4° C. fortwo hours before release of the vacuum and retrieval of the lyophilizedsamples.

The quantities of reactants used in the reduction reaction willgenerally vary depending on the quantities of product desired, andconcomitantly the amount of ketoreductase substrate employed. Thefollowing guidelines can be used to determine the amounts ofketoreductase, cofactor, and optional cofactor regeneration system touse. Generally, keto substrates can be employed at a concentration ofabout 20 to 300 grams/liter using from about 50 mg to about 5 g ofketoreductase and about 10 mg to about 150 mg of cofactor. Those havingordinary skill in the art will readily understand how to vary thesequantities to tailor them to the desired level of productivity and scaleof production. Appropriate quantities of optional cofactor regenerationsystem may be readily determined by routine experimentation based on theamount of cofactor and/or ketoreductase utilized. In general, thereductant (e.g., glucose, formate, and isopropanol) is utilized atlevels above the equimolar level of ketoreductase substrate to achieveessentially complete or near complete conversion of the ketoreductasesubstrate.

The order of addition of reactants is not critical. The reactants may beadded together at the same time to a solvent (e.g., monophasic solvent,biphasic aqueous co-solvent system, and the like), or alternatively,some of the reactants may be added separately, and some together atdifferent time points. For example, the cofactor regeneration system,cofactor, ketoreductase, and ketoreductase substrate may be added firstto the solvent.

For improved mixing efficiency when an aqueous co-solvent system isused, the cofactor regeneration system, ketoreductase, and cofactor maybe added and mixed into the aqueous phase first. The organic phase maythen be added and mixed in, followed by addition of the ketoreductasesubstrate. Alternatively, the ketoreductase substrate may be premixed inthe organic phase, prior to addition to the aqueous phase.

Suitable conditions for carrying out the ketoreductase-catalyzedreduction reactions described herein include a wide variety ofconditions which can be readily optimized by routine experimentationthat includes, but is not limited to, contacting the engineeredketoreductase enzyme and substrate at an experimental pH and temperatureand detecting product, for example, using the methods described in theExamples provided herein.

The ketoreductase catalyzed reduction is typically carried out at atemperature in the range of from about 15° C. to about 75° C. For someembodiments, the reaction is carried out at a temperature in the rangeof from about 20° C. to about 55° C. In still other embodiments, it iscarried out at a temperature in the range of from about 20° C. to about45° C. The reaction may also be carried out under ambient conditions.

The reduction reaction is generally allowed to proceed until essentiallycomplete, or near complete, reduction of substrate is obtained.Reduction of substrate to product can be monitored using known methodsby detecting substrate and/or product. Suitable methods include gaschromatography, HPLC, and the like. Conversion yields of the alcoholreduction product generated in the reaction mixture are generallygreater than about 50%, may also be greater than about 60%, may also begreater than about 70%, may also be greater than about 80%, may also begreater than 90%, and are often greater than about 97%.

7. EXAMPLES

Various features and embodiments of the disclosure are illustrated inthe following representative examples, which are intended to beillustrative, and not limiting.

In the following descriptions, wherever glucose dehydrogenase (GDH) isused, it is GDH CDX901, obtainable from Julich Chiral Solutions, Jülich,Germany.

7.1 Example 1: Wild-Type Ketoreductase Gene Acquisition and Constructionof Expression Vectors

Ketoreductase (KRED) encoding genes are designed for expression in E.coli based on the reported amino acid sequence of the ketoreductase anda codon optimization algorithm as described in Example 1 of U.S.provisional application Ser. No. 60/848,950, incorporated herein byreference. (Standard codon-optimization software also is reviewed ine.g., “OPTIMIZER: a web server for optimizing the codon usage of DNAsequences,” Puigbò et al., Nucleic Acids Res. 2007 July; 35 (Web Serverissue): W126-31. Epub 2007 Apr. 16.) Genes are synthesized usingoligonucleotides composed, e.g., of 42 nucleotides and cloned intoexpression vector pCK110900 (depicted as FIG. 3 in United States PatentApplication Publication 20060195947) under the control of a lacpromoter. The expression vector also contains the P15a origin ofreplication and the chloramphenicol resistance gene. Resulting plasmidsare transformed into E. coli W3110 using standard methods. Examples ofcodon-optimized genes and the encoding polypeptides as well are listedin Table 5. The activity of the wild-type ketoreductases is confirmed asdescribed in U.S. provisional application Ser. No. 60/848,950.

TABLE 5 Abbreviations, Source and Citations for RepresentativeKetoreductases Microorganism from which enzyme Polypeptide wasoriginally Genbank GI Polynucleotide SEQ ID No Ketoreductase identifiedAcc. No. Number SEQ ID No or Source ADH-CM Candida magnoliae AB036927.112657576 SEQ ID SEQ ID NO: 131 NO: 132 YDL Saccharomyces NP_010159.16320079 SEQ ID SEQ ID cerevisiae NO: 137 NO: 138 ADH-LB Lactobacillusbrevis 1NXQ_A 30749782 SEQ ID SEQ ID NO: 1 NO: 2 ADH-RE RhodococcusAAN73270.1 34776951 SEQ ID SEQ ID erythropolis NO: 133 NO: 134 YGLSaccharomyces NP_011476 6321399 SEQ ID SEQ ID cerevisiae NO: 135 NO: 136YPR Saccharomyces NP_010656.1 6320576 SEQ ID SEQ ID cerevisiae NO: 139NO: 140 GRE Saccharomyces NP_014490.1 6324421 SEQ ID SEQ ID cerevisiaeNO: 141 NO: 142 ADH-LK Lactobacillus kefir AAP94029.1 33112056 SEQ IDSEQ ID NO: 3 NO: 4 ADH-SB Sporobolomyces Q9UUN9 30315955 SEQ ID SEQ IDsalmonicolor NO: 145 NO: 146 ADH-SC Streptomyces NP_631415.1 21225636SEQ ID SEQ ID coelicolor NO: 143 NO: 144 ADH-TB ThennoanaerobiumX64841.1 1771790 SEQ ID SEQ ID brockii NO: 153 NO: 154 ADH-CP CandidaBAA24528 2815409 Julich Chiral parapsilosis Solutions Cat. No. 03.11DR-LB Lactobacillus brevis ABJ63353.1 116098204 Julich Chiral diacetylreductase Solutions Cat. No. 8.1 ADH-HE Horse liver DEHOAL 625197 SEQ IDSEQ ID NO: 155 NO: 156 ADH-CB Candida boidinii CAD66648 28400789 JulichChiral Solutions Cat. No. 02.10 LDH-LL Lactobacillus Fluka Cat.leichmannii No. 61306 ADH-AF Aspergillus flavus P41747 1168346 SEQ IDSEQ ID NO: 147 NO: 148 ADH-001 Oenococcus oeni ZP_00318704.1 48864831SEQ ID SEQ ID NO: 149 NO: 150 ADH-RU Ralstonia eutropha ZP_00202558.146131317 SEQ ID SEQ ID NO: 151 NO: 152 Lactobacillus minor SEQ ID SEQ IDNO: 157 NO: 158

Polynucleotides encoding engineered ketoreductases of the presentinvention are likewise cloned into vector pCK110900 for expression in E.coli W3110.

7.2 Example 2: Production of Ketoreductase Powders; Shake FlaskProcedure

A single microbial colony of E. coli containing a plasmid with theketoreductase gene of interest is inoculated into 50 ml Luria Bertanibroth containing 30 μg/ml chloramphenicol and 1% glucose. Cells aregrown overnight (at least 16 hrs) in an incubator at 30° C. with shakingat 250 rpm. The culture is diluted into 250 ml Terrific Broth (12 g/Lbacto-tryptone, 24 g/L yeast extract, 4 ml/L glycerol, 65 mM potassiumphosphate, pH 7.0, 1 mM MgSO4, 30 μg/ml chloramphenicol) in 1 literflask to an optical density at 600 nm (OD600) of 0.2 and allowed to growat 30° C. Expression of the ketoreductase gene is induced with 1 mM IPTGwhen the OD600 of the culture is 0.6 to 0.8 and incubated overnight (atleast 16 hrs). Cells are harvested by centrifugation (5000 rpm, 15 min,and 4° C.) and the supernatant discarded. The cell pellet is resuspendedwith an equal volume of cold (4° C.) 100 mM triethanolamine (chloride)buffer, pH 7.0 (including 2 mM MgSO4 in the case of ADH-LK and ADH-LBand engineered ketoreductases derived therefrom), and harvested bycentrifugation as above. The washed cells are resuspended in two volumesof the cold triethanolamine (chloride) buffer and passed through aFrench Press twice at 12000 psi while maintaining the temperature at 4°C. Cell debris is removed by centrifugation (9000 rpm, 45 min., and 4°C.). The clear lysate supernatant is collected and stored at −20° C.Lyophilization of frozen clear lysate provides a dry powder of crudeketoreductase enzyme.

7.3 Example 3: Production of Ketoreductases; Fermentation Procedure

In an aerated agitated 15 L fermenter, 6.0 L of growth medium containing0.88 g/L ammonium sulfate, 0.98 g/L of sodium citrate; 12.5 g/L ofdipotassium hydrogen phosphate trihydrate, 6.25 g/L of potassiumdihydrogen phosphate, 6.2 g/L of Tastone-154 yeast extract, 0.083 g/Lferric ammonium citrate, and 8.3 ml/L of a trace element solutioncontaining 2 g/L of calcium chloride dihydrate, 2.2 g/L of zinc sulfateseptahydrate, 0.5 g/L manganese sulfate monohydrate, 1 g/L cuproussulfate heptahydrate, 0.1 g/L ammonium molybdate tetrahydrate and 0.02g/L sodium tetraborate decahydrate are brought to a temperature of 30°C. The fermenter is inoculated with a late exponential culture of E.coli W3110, containing a plasmid with the ketoreductase gene ofinterest, grown in a shake flask as described in Example 3 to a startingOD600 of 0.5 to 2.0. The fermenter is agitated at 500-1500 rpm and airis supplied to the fermentation vessel at 1.0-15.0 L/min to maintaindissolved oxygen level of 30% saturation or greater. The pH of theculture is controlled at 7.0 by addition of 20% v/v ammonium hydroxide.Growth of the culture is maintained by the addition of a feed solutioncontaining 500 g/L cerelose, 12 g/L ammonium chloride and 10.4 g/Lmagnesium sulfate heptahydrate. After the culture reached an OD600 of50, expression of ketoreductase is induced by the addition ofisopropyl-b-D-thiogalactoside (IPTG) to a final concentration of 1 mM.The culture is grown for another 14 hours. The culture is then chilledto 4° C. and maintained at 4° C. until harvested. Cells are harvested bycentrifugation at 5000 G for 40 minutes in a Sorval RC12BP centrifuge at4° C. Harvested cells are used directly in the following downstreamrecovery process or are stored at 4° C. until such use.

The cell pellet is resuspended in 2 volumes of 100 mM triethanolamine(chloride) buffer, pH 6.8, at 4° C. to each volume of wet cell paste.The intracellular ketoreductase is released from the cells by passingthe suspension through a homogenizer fitted with a two-stagehomogenizing valve assembly using a pressure of 12000 psig. The cellhomogenate is cooled to 4° C. immediately after disruption. A solutionof 10% w/v polyethyleneimine, pH 7.2, is added to the lysate to a finalconcentration of 0.5% w/v and stirred for 30 minutes. The resultingsuspension is clarified by centrifugation at 5000 G in a standardlaboratory centrifuge for 30 minutes. The clear supernatant is decantedand concentrated ten times using a cellulose ultrafiltration membranewith a molecular weight cut off of 30 KD. The final concentrate isdispensed into shallow containers, frozen at −20° C. and lyophilized topowder. The ketoreductase powder is stored at −20° C.

7.4 Example 4: Analytical Methods for the Conversion of5-((4S)-2-oxo-4-phenyl (1,3-oxazolidin-3-yl))-1-(4-fluorophenyl)pentane-1,5-dione to(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one

Analytical methods to determine conversion of(S)-1-(4-Fluoro-phenyl)-5-(2-oxo-4-phenyl-oxazolidin-3-yl)-pentane-1,5-dioneand enantiomeric excess of(4S)-3-[(5S)-5-(4-Fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-one.

Achiral HPLC method to determine conversion. Reduction(S)-1-(4-Fluoro-phenyl)-5-(2-oxo-4-phenyl-oxazolidin-3-yl)-pentane-1,5-dioneto(4S)-3-[(5S)-5-(4-Fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-onewas determined using an Agilent 1100 HPLC equipped with an AgilentZorbax Eclipse XDB column (7.5 cm length, 2.1 mm diameter), eluent:water/acetonitrile 50:50, flow 0.7 ml/min; column temperature 40° C.).Retention times:(4S)-3-[(5S)-5-(4-Fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-one:1.3 min,(S)-1-(4-Fluoro-phenyl)-5-(2-oxo-4-phenyl-oxazolidin-3-yl)-pentane-1,5-dione:2.2 min.

Chiral HPLC method to determine stereopurity of(4S)-3-[5-(4-Fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-one.The stereomeric purity of(4S)-3-[5-(4-Fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-onewas determined using an Agilent 1100 HPLC equipped with a Chiralcel OD-Hcolumn (15 cm length, 2.1 mm diameter, eluent: hexane/ethanol 80:20,flow 1 ml/min). Retention times:(4R)-3-[(5S)-5-(4-Fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-one:6.64 min,(4S)-3-[(5S)-5-(4-Fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-one:7.93 min,(S)-1-(4-Fluoro-phenyl)-5-(2-oxo-4-phenyl-oxazolidin-3-yl)-pentane-1,5-dione:10.44 min.

7.5 Example 5: Evaluation of Wild-Type Ketoreductases for Reduction of5-((4S)-2-oxo-4-phenyl (1,3-oxazolidin-3-yl))-1-(4-fluorophenyl)pentane-1,5-dione

KREDs described in Table 5 of Example 1 are screened using NADH andNADPH as cofactors and glucose dehydrogenase/glucose or isopropylalcohol(“IPA”) as co-factor regeneration system. 100 μl of cell lysate wasadded to a deep well plate (Costar #3960) containing 25 μl 5 mg/mlNa-NADP (Oriental Yeast) and 2 mM MgSO₄ in 100 mMtriethanolamine(chloride) (pH7.0), and 125 μl isopropyl alcoholcontaining 2 g/L(S)-1-(4-Fluoro-phenyl)-5-(2-oxo-4-phenyl-oxazolidin-3-yl)-pentane-1,5-dione.After sealing the plates with aluminum/polypropylene laminate heat sealtape (Velocity 11 (Menlo Park, Calif.), Cat #06643-001), reactions wererun for at least 16 hrs at ambient temperature. At the end of thereaction 1 ml acetonitrile (for reversed phase HPLC) or MTBE (for normalphase HPLC) was added per well. Plates were resealed, shaken for 20minutes, and centrifuged (4000 rpm, 10 min., 4° C.). 200 ul of theorganic layer was transferred into a new shallow-well microtiter platefor analysis.

This example will demonstrate that wild-type ketoreductases have verylittle if any activity on 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione.

7.6 Example 6: Evaluation of ADH-LK Variants for Reduction of5-((4S)-2-oxo-4-phenyl (1,3-oxazolidin-3-yl))-1-(4-fluorophenyl)pentane-1,5-dione

Several ADH-LK variants that had been generated are evaluated and foundthat an ADH-LK variant with SEQ ID NO:8 converted the substrate to thechiral(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-oneproduct when evaluated under the conditions described in Example 5 andas listed in Table 6.

TABLE 6 Activity of an ADH-LK variant SEQ Number of mutations ID NOrelative to ADH-LK Activity ADH-LK 0 0 8 8 ~0.008 g/ L · g_(enzyme) ·day

This example shows that an ADH-LK variant containing G7S, R108H, G117S,E145S, N157T, Y190C, K112R, and I223V mutations converts5-((4S)-2-oxo-4-phenyl (1,3-oxazolidin-3-yl))-1-(4-fluorophenyl)pentane-1,5-dione to(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-onewith high stereoselectivity (94% stereomeric excess).

7.7 Example 7: High Throughput HPLC Assay for Ketoreductase Activity on5-((4S)-2-oxo-4-phenyl (1,3-oxazolidin-3-yl))-1-(4-fluorophenyl)pentane-1,5-dione Using Isopropylalcohol for Co-Factor Recycling

Plasmid libraries obtained by directed evolution and containing evolvedketoreductase genes are transformed into E. coli and plated onLuria-Bertani (LB) broth containing 1% glucose and 30 μg/mLchloramphenicol (CAM). After incubation for at least 16 hrs at 30° C.,colonies are picked using a Q-bot® robotic colony picker (Genetix USA,Inc., Beaverton, Oreg.) into 96-well shallow well microtiter platescontaining 180 μL Terrific broth (TB), 1% glucose, 30 μg/mLchloramphenicol (CAM), and 2 mM MgSO₄. Cells are grown overnight at 30°C. with shaking at 200 rpm. 20 μL of this culture was then transferredinto 96-deep well plates containing 350 μL Terrific broth (TB), 2 mMMgSO₄ and 30 μg/mL CAM. After incubation of deep-well plates at 30° C.with shaking at 250 rpm for 2.5 to 3 hours (OD₆₀₀ 0.6-0.8), recombinantgene expression by the cell cultures is induced by addition of isopropylthiogalactoside (IPTG) to a final concentration of 1 mM. The plates arethen incubated at 30° C. with shaking at 250 rpm for 15-23 hrs.

100 μl of cell lysate was added to a deep well plate (Costar #3960)containing 25 μl 5 mg/ml Na-NADP (Oriental Yeast) and 2 mM MgSO₄ in 100mM triethanolamine(chloride) (pH7.0), and 125 μl isopropyl alcoholcontaining 2 g/L(S)-1-(4-Fluoro-phenyl)-5-(2-oxo-4-phenyl-oxazolidin-3-yl)-pentane-1,5-dione.After sealing the plates with aluminum/polypropylene laminate heat sealtape (Velocity 11 (Menlo Park, Calif.), Cat #06643-001), reactions wererun for at least 16 hrs at ambient temperature. At the end of thereaction 1 ml acetonitrile (for reversed phase HPLC) or MTBE (for normalphase HPLC) was added per well. Plates were resealed, shaken for 20minutes, and centrifuged (4000 rpm, 10 min, 4° C.). 200 ul of theorganic layer was transferred into a new shallow-well microtiter platefor analysis as described in Example 4.

This example describes the method that was used to identify KREDvariants improved for 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione reduction.

7.8 Example 8: Reduction of 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione byEngineered Ketoreductases Derived from ADH-LK

Improved ADH-LK variants for the reduction of(S)-1-(4-Fluoro-phenyl)-5-(2-oxo-4-phenyl-oxazolidin-3-yl)-pentane-1,5-dioneto(4S)-3-[(5S)-5-(4-Fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-onewere analyzed in small scale chemical reactions. In a glass vial with ateflon stirring bar, 500 mg(S)-1-(4-Fluoro-phenyl)-5-(2-oxo-4-phenyl-oxazolidin-3-yl)-pentane-1,5-dione,100 mg KRED variant, 0.5 mg Na-NADP (Oriental Yeast), 2.5 ml isopropylalcohol, and 2.5 ml 100 mM triethanolamine(chloride) buffer, pH 7.0, 2mM MgSO₄ was mixed and stirred overnight at 25° C. Reaction samples wereanalyzed by the method of Example 4.

7.9 Example 9: Preparative Scale Production of(4S)-3-[(5S)-5-(4-fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one

Preparative scale production of(4S)-3-[(5S)-5-(4-Fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-oneusing iPA for cofactor recycle. In a 1 liter round bottom flaskthermostatted at 25° C. with Teflon stirring bar, 2.5 grams lyophilizedKRED catalyst was dissolved in 200 ml 100 mM triethanolamine(chloride),pH 7.0, 2 mM MgSO₄. After the enzyme was dissolved, 175 mg □-NADP⁺ wasadded, followed by 5 grams of(S)-1-(4-Fluoro-phenyl)-5-(2-oxo-4-phenyl-oxazolidin-3-yl)-pentane-1,5-dione.200 ml 2-propanol was added, resulting in the formation of a whiteprecipitate. After stirring for 5 hours at 25° C. by which time thereaction was complete, the mixture was filtered through Celite to removethe insoluble protein fraction. Isopropanol was distilled off untilabout 200 ml solution remained. The aqueous layer was extracted twicewith 200 ml ethyl acetate and the combined ethyl acetate layers werewashed with saturated NaCl. The ethyl acetate layer was dried overNa₂SO₄ and after filtration, ethyl acetate was distilled off yielding ˜5g of the chiral alcohol 2 as slightly yellow colored oil. Thestereomeric purity (determined as described in Example 4) of(4S)-3-[(5S)-5-(4-Fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-onewas >99% (S,S).

Preparative scale production of(4S)-3-[(5S)-5-(4-Fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-oneusing GDH and external pH control. A 2 L resin kettle is equipped with amechanical overhead stirrer, pH probe and a port for titrating aqueous4N NaOH. The external titrator (Schott Titronic) is programmed tomaintain the pH at 7.00+/−0.10

To the resin kettle is charged 5-((4S)-2-oxo-4-phenyl(1,3-oxazolidin-3-yl))-1-(4-fluorophenyl) pentane-1,5-dione (120 g) as apowder, followed by dextrose powder (91 g), toluene (200 ml), and buffer(750 ml of 0.02M potassium phosphate and 0.002 M Magnesium sulfate). Thehead plate is fitted and dogged down. All appropriate ports are closedexcept for the pH probe port which is fitted with the pH probe. Themotor is then fitted to the coupling and stirring is initiated to a rateof 1200 rpm. The pH of the reaction mixture is measured and adjusted to7.0+0.1. The temperature of the reaction mixture is brought to 30+1° C.While the reaction is brought to temperature, 0.4 g Na-NADP, 0.8 g GDH,and 2.00 g of lyophilized KRED were dissolved in 40 ml of de-ionizedwater. When the reactor temperature is in the appropriate range, theenzyme suspension is added in one portion while stirring. The titrationprogram is started and the pH is maintained at 7.0+/−0.1 for theduration of the reaction by addition of 4N NaOH. The reaction is stirredat 30° C. for 16 hr. The reactor is sampled periodically and checked forsubstrate conversion by HPLC as described in Example 4. Periodicsampling and analysis is continued until the conversion reaches 99% orbetter.

When the reaction is deemed to be over, stirring is stopped and thebi-phasic mixture is allowed to separate. Clear aqueous layer (240 ml)is removed from the bottom of the vessel as best as possible by syringe.90 ml of this aqueous layer is added to 22 g Celite and set aside, therest is discarded. Toluene (240 ml) is added to the reaction mixture,which is then stirred for 10 minutes and allowed to settle again for 30minutes. Another portion of 180 ml of clear aqueous phase is removed bysyringe and discarded. The stirring is restarted, followed by additionof the Celite and aqueous mixture that had been set aside. Stirring iscontinued for 10 minutes. The reaction mixture is filtered through an“M” sintered glass funnel to remove insoluble material (primarilydenatured enzymes and Celite). The cake is filtered until almost dry.The reactor is rinsed with toluene (100 mL). The reactor rinse is addedto the filter cake. The filter cake is tamped down, then washed with 100ml more toluene and allowed to run dry. The biphasic filtrate istransferred to a separatory funnel and separated. Saturated aqueousammonium sulfate (100 ml) is added to the organic layer and mixedlightly and allowed to separate. The lower (aqueous) layer is removed.The toluene is then washed twice with de-ionized water. After the finalseparation, the resulting wet toluene solution containing the product ischarged to a 1 liter flask and stripped down under vacuum on a rotaryevaporator. While doing this, the heating bath is warmed to no more than50° C. and the vacuum is brought down from 110 mm (initially) to 2 mm.The resulting crude product is an oil that solidifies on standing withintwo days. Yield: 125 g.

All publications, patents, patent applications and other documents citedin this application are hereby incorporated by reference in theirentireties for all purposes to the same extent as if each individualpublication, patent, patent application or other document wereindividually indicated to be incorporated by reference for all purposes.

While various specific embodiments have been illustrated and described,it will be appreciated that various changes can be made withoutdeparting from the spirit and scope of the invention(s).

What is claimed is:
 1. An engineered polynucleotide encoding anengineered polypeptide having ketoreductase activity, wherein saidengineered polypeptide comprises a region with an amino acid sequencehaving at least 95% sequence identity to residues 90 to 211 of SEQ IDNO: 130, comprising a substitution at position X117 with glycine and atposition X190 with cysteine, and further comprising one or more of thefollowing features selected from: residue corresponding to X94 isasparagine, glycine, serine, or a polar residue; residue correspondingto X95 is an aliphatic residue; residue corresponding to X96 isglutamine, asparagine, or threonine; residue corresponding to X101 is anacidic, non-polar, or a polar residue; residue corresponding to X105 isan acidic or non-polar residue; residue corresponding to X108 is ahydrophilic, polar or constrained residue; residue corresponding to X111is a non-polar or aliphatic residue; residue corresponding to X112 is anacidic or polar residue; residue corresponding to X113 is a non-polar oraliphatic residue; residue corresponding to X127 is a basic residue;residue corresponding to X147 is a non-polar, aliphatic, aromatic, orhydrophobic residue; residue corresponding to X152 is a non-polar,basic, or hydrophilic residue; residue corresponding to X157 is a polarresidue; residue corresponding to X163 is a non-polar or aliphaticresidue; residue corresponding to X176 is a non-polar or aliphaticresidue; residue corresponding to X176 is a non-polar or aliphaticresidue; residue corresponding to X194 is a constrained, basic, or polarresidue; residue corresponding to X197 is a hydrophilic, acidic, basic,aliphatic or a non-polar residue; residue corresponding to X198 is anacidic, basic, hydrophilic, or non-polar residue; residue correspondingto X199 is an acidic, aliphatic, or non-polar residue; residuecorresponding to X200 is an acidic or constrained residue; residuecorresponding to X202 is a non-polar residue; residue corresponding toX206 is a non-polar, aromatic, or hydrophobic residue; and wherein theamino acid sequence can optionally have one or more differences at otheramino acid residues in the domain as compared to the reference sequence.2. The engineered polynucleotide encoding the engineered polypeptide ofclaim 1, further comprising one or more substitutions at position X7,X145, and X211.
 3. An expression vector comprising the polynucleotide ofclaim 1, operably linked to one or more control sequences suitable fordirecting expression of the encoded polypeptide in a host cell.
 4. Theexpression vector of claim 3, wherein the control sequence comprises apromoter.
 5. The expression vector of claim 4, wherein the promotercomprises an E. coli promoter.
 6. The expression vector of claim 3,wherein the control sequence comprises a secretion signal.
 7. A hostcell comprising the expression vector of claim
 3. 8. The host cell ofclaim 7, wherein said host cell is E. coli.